seems our engine's are somehow related: mine was also assembled by some goof who managed to crack one of the cylinder heads on installation, some gaskets were in crooked, others (fuel pump gasket) weren't installed at all. Took some time to find the oil leak, I simply couldn't believe someone had "forgotten" to put a gasket in.
I'm on not quite such a tight budget, but I hope I can help none the less. Thing #1 to remember is: take your time and do it properly, othwise you'll be spending much more money shortly. Get as much info as you can before you start. Never use things ONLY BECAUSE YOU HAVE THEM. Always ask yourself wether there might not be something better to get maybe for not even so much money. Here's a "to do" list:


1. Junk the heads, get ones with 67cc chambers or smaller (not under 64cc), stay iron, not alum. Go for small intake runner volumes (160-180), look for heads with the following numbers: 041, 186, 462, 601 (watchout if they have accessory holes)
2. check the block for wear (if it didn't last long chances are you don't need to bore, only hone)
3. check everything for straightness, flatness, cracks,...
4. call Crane, Comp and some more cam grinders and ask for their "best bet" cam. All "normal" cams cost very much the same. Get four or five different quotes from different grinders and go with the cam that's closest to the average of all the specs you got.
5. Stay HEI and get good wires, there are some very inexpensive aftermarket HEIs (like ProComp) out there with adjustable vac advance which will save you on gas when cruising. Might be 80 bucks now, but will save you hassle and gas later
6. If your rods are press fit and the pistons not excessively worn flat top style, keep those. If the rods are bushed, keep them anyway. If the rods are bushed and the pistons dished, get flat tops, hypereutectic.
7. the block will probably not need any machining if you're staying in the region of 350 HP. Honing has to be done to seat and seal the rings properly.
8. ASSEMBLE WITH CARE, TORQUE CORRECTLY

Or forget all of this and buy a book like "how to rebuild SBC" or "How to build max performance SBC on a budget" by David Vizard. Buying books is very often going to give you very good answers, especially if you're new to engine building, like I am. I have both those books and I've read them and they certainly haven't answered all my questions, but about 80 percent of my motor project is set up on findings from those books. They also say some interesting things about "all the rage" items like alum heads, roller cams, forged pistons and so on.
My advice would be: buy some books, they'll save you a lot of money because you understand what you're doing much better, can head in the right direction with things like cams and so on much quicker.
Hope I could help and good luck with your engine,
Max