430

define "reasonable" because just a rebuild kit for these is over $1000 and that doesn't include machine work and very few machinists have the torque plates for these wedge motors. Most original motors are 40years old and show. Most of them had a cam gear break abart and plug up the oil puck up and cause the 2 rear pistons to seize to the rings. I have 3 motors with this exact problem. especially for a '58, goodluck finding a motor at all.
I have picked up motors for the kind of price you are looking for, but they all had their problems. The best one I ever got was a 462 near complete and everything was perfect except that someone removed the oilpan and left it outside. Sorry, can't help you, but goodluck, keep your eye on ebay.