Bigblackcat,
The only modification you need to do is cut and hammer your transmission cover to make room for the shifter that sits atop the tranny.
I have a '61 with that tranny and Patrick's shifter.
Everything else stays just where it is and nothing interferes with your with your clutch linkage.
Same throw out bearing, disk etc...
The Saginaw 4 speed was the same length as the 3 speed I removed and I didn't have to cut my driveshaft.
The yoke for the output shaft was specific to the 4 speed so make sure you get te right one
