All this talk of engine swaps reminds me of a conversation I had many, many
years ago with a friend who had a VW bus - probably 'circa mid sixties.

This was when a popular swap was to put a corvair engine in place of the VW
motor. His story went as follows:

"So the mechanic talked me into putting a Corvair engine in the bus,
something like 3 times the horsepower of the stock VW motor. Still couldn't
go any faster, but I could get up to speed really fast! What I didn't
realize was that even though the bus now had lots more power - I was still
handicapped by the 4-speed transmission and the stock ratios."

Something to consider.