I just purchased a Remington 7615 Receiver - that is about it parts wise. Looking to build it out as a .350 Legend pump action. (from Remington this was a pump action in 5.56 fed via AR-15 magazines)

How many parts transfer from Remington 870 and 7600 (my thinking is nearly everything from 7600 should work, but I may be surprised.
Obviously mag well and associated components will not transfer over, bolts faces will be different.

I have read the Australians have set up 7600's for barrel change-out to different calibers. That appeals to me

Any top tier 7600 smiths to recommend. Recommendations for forums that may cater more to these guns (probably something Pennsylvania or neighboring states)

Any tips/recommendations appreciated.

I may have bit off more than I can chew, maybe not. Time will tell.

Thanks in advance.