I would suggest you take the time and do it yourself. Buy the necessary tools (installers, all measuring equipment, grinding and tapping, files, picks, a few good how-to books, sealants, lubes, etc.) and now you have everything the next time you do it. And in that one time you have learned all the knowledge that the spendy 'big-time' shop knows and then applies. I don't know. I'm sorry but I think you get my point. The only way you'd know for sure is to do it successfully yourself. Hypothetically, if you sold it, the buyer is likely to pay you more for the big-name assembled engine. IMO it's even worth something IF you mention the shops name in vanity once you've patronised them.