Got lucky on my 88 C1500.
Rust-free CA truck. Daily driver work truck, 4/6 drop, mild 350, Edelbrock headers, ported big blade throttle body, K&N cold air package, 7004R. Idles so smooth I have to look at the tach to see if it's running.
(Paint was like this when I bought it)
I'm using these:
Fit is fantastic, but nobody can say for sure if they will clear your floor, so many variables. I can just say they work for my 70 SBC, angle plug, Competition Engineering stock height poly body and motor mounts.
I thought it was cast iron so a regular distributor gear could be used.
I'm going through my files to try and find a pic of my old ZZ4 billet steel cam that shows machining between the lobes that is much smoother than that.
Cleared a 71 Camaro even with a 1/2" phenolic spacer. Ended up with about 7/16" clearance to the stock hood. Holley carb. dropped base 3" K&N. It is close.
That's the Air-Gap manifold right?
I tried using a gauge on the front and a sensor for electric fans in that rear port. It didn't work. It's the manifold design. Looking at the port it sure looked like it would. It would be interesting to try switching them for a test.
I'm thinking yours...
I can't say enough good things about the LT-4 Hot cam.
The ZZ430 I have in my 67 Camaro of course has one. 1.6 GMPP roller rockers. Works great with the Fastburn heads. Awesome power band, and idles like a stocker (which you may or may not like). Built the car in 2001 and still runs great.