Go all out, buy a Dart or World Block $4000, Top of the line Scat stroker and Arias pistons $3500 (can buy cheaper if you want) $2500 Heads, $500 manifold, $400 cam, $500 dissy/leads etc, $500 sump, $300 waterpump, $1000 carby, $1000 for machining/balancing, and another $1000 for good luck.
$15k, assemble it yourself, you would have a very light, extremely powerful, 470+ cube Windsor