From HSCA Volume 9:

Zoppi was reinterviewed on March 31, 1978, and on April 5, 1978.
The report of the March 31 interview states:

His best recollection was that during September or October of
1958, Ruby offered to write McWillie at the Tropicana to get them
airplane tickets so Zoppi could review the acts at the Tropicana
to help McWillie's business.  The OK for trip was received
approximately December 8 or 9 (or 10-12) and the trip was to
last. 4--5 days. Zoppi wanted to be back for the holidays. They
would pay their own way down and be reimbursed: this was the
common practice for journalists reviewing acts. In late November,
Jack Entratter and Al Freeman called inviting Zoppi to review a
big anniversary show at the Sands in Las Vegas. Zoppi said (as he
had written in his article) the show was a "summit meeting" show
featuring Frank Sinatra, Dean Martin, Sammy Davis Jr., Joey
Bishop, and Peter Lawford. Zoppi figured there wouldn't be
anything "like this" in Cuba so he decided to postpone the
trip and told Ruby he would meet him down there after the new
year on approximately January 4. Ruby told Zoppi he would go
down, stay down there and meet Zoppi in Cuba. Zoppi then states
he never went down due to Castro's takeover in January. He
vaguely remembers Ruby told him he had a good time in Cuba. He
doesn't know if Ruby had been there before or not.

On April 5, 1978, Zoppi was questioned further about the dates of
the proposed trip to Cuba. He was also shown the letter which
McWillie had given the committee, which had reminded McWillie of
Zoppi's role in Ruby's Cuba trip. Zoppi authenticated his
signature on this letter. It was pointed out to Zoppi that
Castro's takeover did not immediately prevent travel to Cuba.
Zoppi then called the Sands Hotel to obtain information about the
big shows during the 1958-61 period in order to determine which
show he had reviewed. He stated it could have been the December
1958 show with Rowan and Martin, the December 1960 show with
Marry Allen and Steve Rossi, or the December 1959 show with Dean
Martin.  He thought it was the big show with Frank Sinatra, Dean
Martin, and Sammy Davis which he had referred to in his initial
interview; it had taken place from January 20 to February 16,
1960.

After reviewing all the show Zoppi admitted he was very unsure
about the date of the scheduled trip to Cuba.  Zoppi recalled
that the alternative trip on January 4 was probably prevented by
Castro's takeover.  Castro assumed power in Cuba on January 1,
1959; he severed diplomatic relations with the United States on
January 1, 1961. Zoppi agreed that perhaps Ruby had gone to Cuba
in August 1959 on vacation and the trip Zoppi and Ruby were to
take was an entirely different, trip.

The committee again spoke with Zoppi on September 15, 1978.
Zoppi repeated that the trip to Cuba was originally scheduled for
December 11, 1958, but he postponed the trip so he could attend
and review the December anniversary show at the Sands.  He alsosaid that when Castro took over on the first of the year, he
decided not to visit Cuba.  Zoppi stated it was possible the trip
was cancelled because of the break in diplomatic relations on
January 1, 1961, but believed the trip was cancelled as a result
of the Castro takeover on January 1, 1959.  Zoppi also stated
that Ruby did not give him an airline ticket.  He indicated that
sometime later, Ruby asked Zoppi why he did not go to Cuba and
Zoppi told him it was "because of all that trouble."

Zoppi also supplied the committee with an article he wrote in
1973 called "Ruby in Retrospect" In it, Zoppi stated:

Jack had a good friend named Lewis McWillie who was a casino
executive at the Tropicana in Havana. He asked McWillie if he
would like me to fly to Cuba and do a story on the Tropicana's
show. Lew agreed and said he would send a pair of plane tickets.
The date was set for December 17. 1960. By coincidence, I
received a call from Jack Entratter at the Sands Hotel in Las
Vegas inviting me to "the summit meeting"--an unprecedented show
featuring Frank Sinatra, Dean Martin, Sammy Davis, Joey Bishop
and Peter Lawford. I called Ruby and told him I would have to
postpone the trip to Cuba until early January because I wanted to
see the Sands show. He said he would depart as scheduled and see
me in Havana "right after the first of the year."