'69 225 into a Valiant with a 170

I can't seem to find a flywheel that will work, and I'm a little confused about which oil pan and pickup I would need to source.
Use the oil pan and pickup from your old engine. Go to "parts wanted" and put a post for a slant six flywheel from 1968 or later. pretty sure you can find one. Needs to be from a car or truck with the car transmission, not the top loader truck trans. Or take your flywheel to a machine shop, and have them open up the large center hole. The bolt pattern is the same.
Another option is to used a 1968 up 273-318 LA flywheel and "elongate" one bolt hole.