[Jeff Lee]

Just watched the machine shop place 8 sleeves in a 427 SO block to be run as a 428 CJ in a '68 FB Mustang Stocker. Geez, those 428's sure make power (this is a top-qualifier car), but boy, what a crappy block! Cylinder walls are WAY thin. I would say that if I were to run one (and I would), it would be money WAY ahead to buy the NHRA legal Dove Engineering block. Hopefully your brother gave you the car as those aren't cheap bodies.
The weight break as a 428/335/345 4-speed is 9.47 and these cars run SS/G, SS/H & SS/I.
That's or 9.00 or 9.50 or 10.0 x 345 HP + 170 for driver.
Edelbrock heads carry more HP.
Optional 428 engines are as follows:

345 HP = SS w/dished pistons & heavy valves
360 HP = SS w/flat top pistons, lightweight valves & CJ heads & lightwt comp.
375 HP = SS w/flat top pistons, lightweight valves & Cad heads & lightwt comp
I have a question...whats a "lightwt comp"?

You might also consider a 390 combo. They run very good also.