67 Ford P/U. Was told it was 390 from previous owner. FoMoCo didn't put 390 in trucks til 68 and vin tab agrees it was a six. It's been cammed, headers, angled valve job with intake and exhaust polished. Front of motor is stamped "352" so I know it is an FE. Top end rebuilder say it was 4.05 bore bored .030 over. Block # is C6ME-A and head # is C7AE-A. In my SA Design "High Performance Book" by George Reid the only time I find this block number and head number together is in a 410 Merc. or a 66-68 390 High Performance w/ Thermactor. What is a Thermactor? Thanks for any assistance