Big block swap question

[99-LS1-SS]

I plan on putting a big block in the Blazer after I get the body and frame closer to acceptable. My question is related to the transmission linkage. From what I've been able to determine the TH350 and the TH400 use the same linkage coming from the steering column. My question is, will that still be the case if I put a big block in the truck using 1972 big block motor mounts? Don't the factory style motor mounts for the big block move the motor forward some?

I know I'll have to get a custom driveshaft so that part doesn't worry me. The linkage is my next hurdle. I feel comfortable moving the transmission mount to where ever it needs to be and mounting it to the frame after I've got the engine in.

Am I missing anything obvious? If this topic has been discussed I wasn't able to find it in a search. If there are a bunch of links already just post them up.

Thanks!