I am just about ready to start stuffing a BBB into my 1973 Apollo that had a 350 V8. The current TH350 with shift kit works great so my plan is to use this trans until I have a problem then switch to a 4 speed auto. I have the following questions. I know the trans bellhousing pattern is the same between the 350 and 455 but can I use the original flexplate and torque converter? Is the starter position and gearing the same? Assuming the TH350 is a short term solution what would be the best option when going later to a 4 speed auto?
Use the flexplate from the 455. You can use the same TC. As for future use, you will have to have a 4spd auto built to handle the 455 torque. You can use the 200R4 but will cost some $$$$ to be built. If this is a city cruiser, I would get a shortshaft TH400, best trans GM ever built.
