I just bought a mid to late 90s LT1 327 going to rebuild it. I just want to know if it will bolt up to the factory transmission in my 85 Delta 88.

 

No, unless you have a 200 4R overdrive with dual pattern bolt holes.

 

FYI, they did not make a 327ci LT1. The 5.7 350ci versions did have a number 327 cast on the side of the engine.
They made a small 4.3L version of this also. These have a 4.3 cast into the block above the belle housing area.

It will only fit your current trans if it has a factory dual pattern trans or if your car originally had a 305 Chevy engine in it.

 

It will also violate your transmission internally unless you beef it up. Why not keep your Olds with an Olds engine? Plenty of cheap Olds 350s around that you can build stout.

 

Honestly if you're going the LT1 route use a 4L60E and use the stock computer to control it. Much easier than trying to use a TH250C/TH350/200-4R. If you want to keep the LT1 AC compressor you need to clearance the frame and front crossmember on the passenger side. The back of the compressor hits the frame.