I'll toss in some thoughts / opinions as well. Like a lot of guys, my thoughts ramble and I type what I am thinking in the moment, but I'll try and keep it all "straight". I would think you'd be better served ( after reading the above) to remove and disassemble the motor first. Inspect the interior components and evaluate the needs before the wants. It may simply need a freshening!

The one thing I would do is replace the rear differential gears. 2.7 is a good highway ratio, but if you want to do street and strip you need to have something that starts with a 3.0 to 4.0 ratio, I would also advise you to watch for the "combination" because the cam has to work with the Cylinder Heads and the Torque Converter as well, and even the tire size / O.D. and rear axle ratio come into play. If you want serious power, and want to do racing - then consider aluminum heads, if you want to use a ceiling of 4 to 5 thousand rpm, then the advantage of high flowing heads will be wasted. Same goes for the camshaft you choose. It sounds to me that you'd be better served with a "torque" cam, like they grind for RV's and trucks. You are wanting the most power at a lower rpm.

Like I said, just some thoughts, hope it helps and gives you some things to think about. It is good to see you here, welcome aboard!