I usually fit all of the parts and then re finish. It is very easy to mark the finish while trying to fit a part . Good choice on frame I am on my way to pick one up for a build I am doing,as the parts I have are satin I plan to get the stainless steel one. By all means send it to Shuff he has done some for me and the parts all seemed to match although they were from unknown makers and dates most were Remington Rand. BTW I think the frame you want is a copy of the GI frame I rarely use the duck bill grip safety on a GI replica so I do not like my frame cut for it. Anyway I can make that cut myself if I need to.
Good luck on your build and any help I can be just ask.BTW my stage name comes from being a military gunsmith and putting arms back in service with any serviceable part and damn the markings not matching!!