The Targetmaster product line was marketed as the cheeepest possible GM-warrantied engine replacement for a revenue-producing vehicle. Think of a phone company van; imagine how the phone company would want their old dead van back on the road rather than paying for a new one.
The actual motor itself was usually a failed unit from final test (run-in) off the production line at the engine plant, "repaired". I've seen some of the MOST AMAZING things in those; from ONE crank journal undersized, to ALL crank journals oversize with no oil clearance, to core shift in the block that rendered it useless, and so on.
Part number for part number, they typically matched the lowest performance engines of the day. Most of them were truck motors. Again, remember, think "fleet service unit". Phone company van. Typically they were the 8¼:1 dished pistons; 76cc heads either 882, 624, or 993 casting; 442 casting crank; sometimes "O" or "B" rods, since they were usually a truck motor; 929 cam http://store.summitracing.com/partde...2D12%2D105%2D3
; often 4-bolt mains (again, truck stuff). In no manner way shape or form a powerhouse; just, enough power to get a failed revenue-producing member of a large fleet customer's fleet back on the road and producing revenue, at the lowest possible cost to the customer.
250 HP or so on an engine dyno, MAYBE. The IDENTICAL motor, part # for part #, was "rated" at 165 HP in an Impala or C10 or G10 350 2-barrel. So I don't know where you'd get the idea that an intake or carb would coax more than 250 HP out of it.
I don't have any "good" info. Info is what it is, neither good nor bad. Sorry, I can't help you with that part.