First, whoever told you you couldn't make a 396 go 10s, well, NEVER ASK THEIR ADVICE AGAIN! There were 10 second street SS396 Chevelles in San Bernardino in 1973. Rowdy puppies, but got the job done!
The "428" is a great combo for a truck. It's basically the same bore/stroke combo as a 428 Pontiac, and when you use a 366 block, you get the "long" rod and it ACTS like a 428 Pontiac. The shorter rod required in the short deck would make for quicker revs but at the cost of some torque. For a street machine, it would be good for one that didn't eat as much gas as a "big" motor. Wouldn't go as quick, either, but still be fun.
If the crank is a "real" 396 (the one you now have), the forging number is 6223. If the "parting line" is real skinny (casting), it's a 402 crank and not suited for any real power. If you have the forging, a MUCH better approach would BE the original stroke. Those heads would easily feed a 396 well past 7,500. THAT is the short-stroke BBC's advantage. It can rev 'til the cows come home. Yes, bigger can be faster at a more mild level. But NEVER underestimate a 396 or 427. Just when you do, they'll jump up and bite you!