Upgrading a stock LS1..bang for buck

[DRJDVM's '69]

Did motor teardown.... All the bearings are toast.... One lifter had eaten a roller and wiped a cam lobe....There was water in the oil so essentially there was no lubrication...so far no real idea how if got there.... WTF.... Motor only had 55k on it
Can a head gasket go bad from the car just sitting?... Other than head gasket or crack, how does water get into oil?

So it's a rebuilt.... New bearings, cam, lifters, block prep etc

Leaning towards just sticking with stock head and go more aggressive on cam but not enough to have smog issue

Unless someone has some stock ls6 heads they want to sell

[2BFAST]

I have a 2000 LS1 im putting in the ol ladies 69 Camaro. Details below on my mild build:

00' LS1 short block
LS6 intake
Factory casting 243 heads milled .015", cleaned, and valve job w/ new valve seals
ARP Head Bolts
ARP Crank Bolt
TSP hardend pushrods
Comp custom grind cam - 227/236 - 614/621 @ 111lsa 108icl
Comp cams rocker trunion upgrade
LS7 Lifters
PAC 1211X valve springs
LH8 oil pan/pickup tube
GM LS6 high volume oil pump
LS2 timing chain
BRP oil pump girdle
44# Injectors

Circle D 278mm 3200 stall converter