my 307 dilemma (warning, not a chevy truck lol)

[etizz]

Hey guys I'm new here and I hate to threadjack as well but I'm not sure where else to put this so if you could at least read it I'd really appreciate it.
I got a couple questions on a build i've been working on since
early spring last year. To sum it up i put a 307 sbc out of my dad's 73 nova
into my 85 rx7 and i've been driving it around for awhile but i feel like i
picked the wrong parts to put on it when i built it. heres what i have.

307 sbc, stock bottom end rebuilt, 882 casting 76cc heads refreshed and milled .010,
edelbrock performer rpm dual plane intake, holley 600, summit k1104 cam
(.465 lift int/exh 282/282 duration), shorty headers,
hei distributor with msd streetfire ignition, r45ts ac delco plugs gapped at .040
Behind it is a T5 5speed from a camaro and a ford 9 inch 3.55 gears.

heres my dilemma. as you can already see this was a bad combo to begin with lol. I've learned the hard way realizing that this car didn't have too much power given the horrible compression ratio. I got advice to get some 416 casting 305 heads with 58cc chambers to bump my compression up to about 9.5 to 1, so i found some from a guy for 40 bucks and had koi's machine shop inspect and redo the heads with a .006 mill for flatness and a valvejob with new springs n everything.

so the story goes i rip the old heads off the car and put these 416's on and i could not get the car to start no matter what the valve tightness was or the ignition timing was either i tried everything. i did a compression check and here are the results...
cyl
1 - 70
3- 120
5-115
7-120
2- 120
4- 120
6 -110
8- 90

those numbers seemed awfully low to me i just rebuilt the bottom end not even 10k miles ago(keep in mind i did however not bore it even .10 over and used same size rings. might be the issue) anyways it wouldn't even wanna start it would just crank and crank.

do i need to rebuild the bottom end again?

i checked the valves for leakage and had no luck finding anything wrong with the heads, not cracked, not anything that i can tell nor my dad could either. do i need special rockers or something? im clueless at this point.
since then i put the 76cc's back on and it started right up again and i drove it for awhile before finding another car to daily while i figure out whats going on with this.

so heres what i've been considering. i have an 020 casting block which apparently from what i've heard are better for boring out to a 4" bore ? can someone confirm that?
which would give me more options as far as pistons n rings availability and more power obviously.

i would really like to retry these 416 heads after that and see if the results are any different otherwise im just gonna spend my money on a gen 3 vortec motor with fuel injection cuz i give up with this engine lol

any advice would be greatly appreciated. Thanks!