You have to toss those catalogs away and start networking, going to swap meets and shows and meet the folks that can help you out with parts and advice.
On my 354 I bought three 6-71 cores for $20 each... Took my tools along and pulled them right from the diesels. Bought a BBC drive kit off if flea bay for $250-ish... Had a blower shop in Oregon do the conversion for $280.00 (Dean Blowers). Plus another $90.00 for a rear cover, gaskets and such.
$2500 in machine work, $800 Venolia pistons, $165 cam, NOS Cragar intake for $300...
Do your homework and you can save a bundle. If I had to buy out if those catalogs I'd be priced out of the hobby.