Hey Dave. The car that you pulled the 410 out of was probably a 1966 or 1967 as they were the only two years that the 410 was used in the Mercury cars. I have a 410 that I just pulled out of a Mercury Park Lane. I was going to bore it out to be equivalent to the 427 or 428 but wasn't sure how thick the remaining wall would be. Any help on whether I could do this or not would be greatly appreciated. Thanks