That would be my recommendation also. Try what you have and go from there. If it's no good, post an ad here and find another one. I purchased a trans from a fellow Stovebolter a few years ago for a 54 I was working on for a friend. The price was reasonable and it worked well.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine