Too big of cam?

I'm soaking all of this in, learning, and loving it, thanks again! You all have great things to say and I feel like I should respond to everyone but can't of course so I will add what I can.
This is my daily driver and I need it daily, so unless something bad happens I don't plan on taking off the head or anything that radical at this time. The guy that I bought it from said it was an aluminum block engine and he would like to buy it back if I ever upgraded to a V8, (he kept saying that it was 'ready for a big block'). I have no reason to not believe him about the aluminum, everything else he told me has been true. When I was done paying for the car and backing out of his driveway the last words he said was "Don't punch it or you will blow a head gasket". He must have known how hard they are to find? I hope. Other than trying to stick a magnet to the side I'm not sure I know how to tell the difference, any special tricks to tell aluminum or not? Personally I don't see what the advantage would be to have the aluminum if you have to be careful with them and risk blowing them up with too much power. The weight difference must be better than I thought. But it came with the car (not originally), I like it, and don't plan on changing it out, just want to coax out a little more giddyup.
The previous owner is a retired railroad mechanic, did all of the work to the car himself and it all seems to be quality work (except for the paint job, it sucks). He passed to me stacks of receipts, he kept almost everything thank God. He installed 10" disk brakes on the front (drums still in back) and installed sway bars on both front and rear. The rear end is 83/4 open with 323 gears. Front end needs a little tweaking according to Les Scwab and the tires are around half life. He has redone the steering box too but I haven't looked hard enough for that receipt yet so don't know much about it except it steers sweet as long as I'm moving, no power steering.
I think I'll start with the easiest cheapest things first, (right after a trip to Schwab), like valve adjust, check for leaks, rebuild the carb, then look for 2 bbl intake, 2 bbl carb, HEI, bigger exhaust, stall converter.................HOLY CRAP, WHAT HAVE I GOTTEN MYSELF INTO?? :rolleyes: