the chain is not a big deal have run that chain set in many retro mark 4 with mark 6 cams and have use the pro billet set #cp1019 set and have drill and tap the mark 6 for the mark 4 timing covers and did a mark 6 and used all mark 4 tin oil pan and timing cover with billet mark 4 caps with the two pice gear main seal and 1/2 of the rear main seal adapter this block was a 502/502 that is now a 540 twin turbo and that bike chain set is use in the 502/502 if that cam is a #12551622 it will work fine