Three Speed to Saginaw Car Four Speed Swap- Column Shift

[theastronaut]

I'm looking into swapping in a Saginaw four speed from a car (not the truck granny low four speed) into my '66 that has a 250 and three speed on the column. I'm wanting to keep it column shift and add separate cable under the dash for reverse.

What is involved with swapping from the three speed to the four speed? From pics it looks like the four speed has a longer tail shaft, I'm guessing I'll have to shorten the drive shaft? Can the four speed hang from the stock bellhousing or will it need it's own rear crossmember for support? I believe I'll have to lengthen/modify the shift rods, I can weld so that shouldn't be a problem. Anything else to look out for?

The three ring Saginaw ratios from lower powered cars are 3.50, 2.47, 1.65, 1.00 compared to the 3 speed's 2.94, 1.68, 1.00. It currently has a 3.73 R&P. I could swap to 3.08 gears and the overall ratio in first would be the same while dropping about 600 rpm at 75 mph.