A 428 or 410 Merc. crank. Ford put the 428 crank in 390's to make a 410 cu. in for the Mercury line. With a .030, this should put you close to 420 cu.in. his should be good for almost 30 ft lbs on torque, which will be noticable.
BTW, I understand some early 352's and 390's can be overbored ( with sonic testing of course ) to a std. bore 428. Use the 428 crank and now you have a 428!
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