jjlock59

I have a 75 f-350 with a 67 428 thunderjet motor I burned a valve (I know I DONT want to hear why)My question .. What can Iexpect to lose in performance if I put the original FT 390 heads on the 67 motor?The FT heads have the inserts for unleaded gas but the valves are a little smaller I NEVER go beyond 3700 rpm have a mild towing cam and a 1400 stall converter on the c-6 tranny. Also the original motor was a reverse 105 390 4 bbl FT engine. Any input would be helpful Thanks