I also purchased an M60 from Don about a year and a half ago--Saco Lowell in E4 Configuration--the gun was very well represented and I had a seamless transaction.
I have a VGC to EC Transferable Colt M16A1 that I would like to trade toward a Fleming H & K Sear--if interested I also have a late generation Ares Shrike to go with the gun.
I can provide several references from within the NFA community--