Dan
Talk to folks who own those cars from ERA, FFR and UM. If you are like me trying to replicate the car as they were in the 60's none of the choices are separated by price at the end of the day. FFR is easier to get started however a choice IRS FFR will cost as much as an ERA if all the correct details are added later as that is where the cost is.
No slight here: (as this statement can be used with any other car)
A base full donar FFR will cost less than and ERA, SPF or UM for sure.
A FFR with IRS, pin drive, Smiths, 427SO, correct seats, OEM roll bar,
oil cooler, cockpit vents, Wilton carpets, Lucas Lighting and other details will still cost a pile of dough.
There are no deals in this hobby. Specialty parts and authentic parts cost $$$$$.
If you pick a car from ERA, FFR, UM, KMS, SAI, SPF or a couple others you will be all set. Just remember it is the details that cost the $$$ some companies charge more out of the gate but they usually offer more of those costly details up front than do others.