It's just MHO, but it wouldn't be a 427 windsor in a Mk I. It would be a 4.125x3.25 347c.i. in a 4 bolt main, 8.2" deck, alloy block, forged or billet crank, high dollar I-beam rods, JE forged pistons w/lightest pins money can buy, internal balance and a solid roller cam w/Crower HPPO lifters. AFR 205 heads with Jesel shaft mount rockers and the best valve springs money can buy (for God's sake don't use the stock AFR springs.)
But that's just me. It's your bicycle, you've got to decide how to pump up the tires! (My wife doesn't care how the tires get pumped up, as long as she gets to ride the bike.
Lynn