Probably in the neighborhood of 700 HP, but doesn't mean that it would perform like 700 HP, because torque plays a major roll with a small inch motor. Mark/Spib's motor performs like it does in a 3,000 lb car because it has a good combination of HP and torque.
Example: the motor in my Malibu is a 377" motor, with a god awful cam and Brodix track 1 heads on alcohol injected my car weighs 3250 Lbs with driver. The very best it's ever ran was 6.52 in 1/8 and 10.59 @ 125 in the 1/4. It's a total slug in my opinion. When i first built it, i put in a 1900 lb dragster, it went 5.15 in the 1/8 and 8.23@ 158 in the qtr. Bottom line it's probably making about 650 HP but has no torque to speak of. The cam is just too big and the duration is too long. Last yr i built a 388", junk motor, for a friend $600.00 rotating assy (his budget) on alcohol with a toilet bowl. It went 6.30's @110 in the 1/8 mi. in a 3,000lb camero, it also had 1.27- 60ft. times. Something that my $3,000.00 short blk 377" would never do. Again it depends on the weight of the car, and torque is KING not HP.
O'h by the way the junk 388" motor broke a valve head off after about 25 passes and is now useless junk. :cry:
JMO
Zip.