You know what bud you ARE WRONG! There is a guy with a 4th gen camaro, 3.4L iron head, which in it's best day made about the same power as a 3100, and guess what? he puts LS1s to shame, over 300 HP and over 400 ft/lbs of torque (this is just one case, there are others, ever looked at midget car racing?). Done right , the 300ml difference in engine displacement won't effect over power out put much.
Let's look at the fact here:
V8 of any kind into a J-body, let's assume a RWD conversion, ok, so if you could in fact buy an engine for $9000, that has no accessories, so another $500 to $800 for all the accessories, now where getting close to $10000, before teh engine is even placed near the car to get installed.
Now look at the chassis work, usually drivetrain placement conversions like this cost about $5000 for chassis work alone, so we are now near $15000, take into account the new brake lines, fuel lines, rad, hoses, likages, new interior sheet metal for the tranny tunnel, rear wheel wells, all the little detail stuff, etc, you're usually looking at another $5000 or so, so now we are at just under $20000 for what? about 400HP, when that could have beenmade for far less, and far less down time, by adding a turbocharger system, and/maybe building an engine that will bolt into the engine bay, for between $1000 to $5000 total investment (depending on actual cost pf parts and ability of the owner to install/fabricate the system) and be more repected when you do prove how well a FWD car can run?
Even attemping to drop that V8 in your car as FWD to keep it apples to apples, you are still going to spend about $5000 in chassis work, adaptors, and custom parts, hoses etc, so you'r still at just about $15000 for a V8 in your car, which if done in a FWD aspect will greatly upset the balance of the car and make it only good in a straight line (for the most part).