R3 resto block billet 4 bolt main caps
I have a set.....I think they are Milodon ( Gold irridite finish ) for the stock block.........I have no idea if the register is wider for the R-3 / replacement block , but they might work for you.
If you have some measurements for the width of the cap and the width of the register where the cap fits into the block , I can check and see if these will work for you.
Let me know if you are interested.......I got them cheap and will let them go for about the same.