650 Gross HP ?
Yes easily , we built a 440 using stock 915 closed chamber iron heads ported & a solid flat tappet cam , nothing radical & dynoed at 400 HP at the tires which is 640 HP gross rating , completely drivable , no stalling at lights etc .
I also did a 70 real 440+6 shaker 4 spd Cuda it look bone stock from the outside , same combo inside , it is a monster , my friend who also builds cars drove it & said it was one of the fastest cars he has ever driven , it is in Calgary area also
. If I was still in Calgary I would help you build it !