I've done 2 so far, one was 4.125 X 3.795 with a 6.25 rod, 406 CI RR worked out to 1.65ish and a comp height of 1.09, I thought this would of made a great Boosted engine, but it was built NA. Apache heads with 2.18 Intake Howards .600 lift cam Edelbrock EFI intake
the 2nd we pushed the limit on the sleeve, Darton says max bore for the MID sleeve system is 4.155, but we went 4.185, with a Molnar NHRA 3.59 crank 6.3 Length rods . 395CI 1.75 RR and 1.12 Comp height, and they spin that thing HIGH.
you could in theory build a 460 with the Darton sleeves, 4.155 X 4.25 , with a 6 in rod you would need a 1.125ish comp height , with a 6.125 rod you'd need a hockey puck `1 inch ish, now a Carrillo Pro 66070H rod would be a good compromise 6.07 length. bad thing is those rods are about $300-400 each....but then again everything in this "bench Race" 6.1 is going to be costly
I think you'd have issues with that short of a comp height. Boost pistons require .250 minimum from the top of the Piston to the first ring groove. But like you said everything would be big money.
