Factory roller 360 and 308 head questions.

Great forum you guys have.
After putting together a warmed over Slant for my 69 dart, I’ve decided that I went the wrong way…Ahh I coulda’ had a V-8.

So I bought a 360 out of a 1990 B350 Van. It’s a factory roller engine, with 308 heads.

Everything is at the machine shop right now, they’re doing the normal stuff .030 bore, .010/.010 on the crank, and all the hot tanking.
They magna fluxed & bead blasted the heads and have given them a clean bill of health, I’m having them install Milodon Stainless 2.02/1.60’s. Heres what I’m considering for the build:

Stock roller block
Stock crank and rods
.030 Speed Pro H116CP Hypereutectics
9.5-10:1 compression
308 heads as cast w 2.02/1.60
Comp XE274HR, XE280HR or XE286HR (I’m leaning towards the 280)
PRW Shaft Style Full Roller rockers
Performer Air Gap

Can you guys shed some light on a couple concerns?
What is the chamber volume on a 308 head?
Can I expect any problem using factory lifters with one of these cams?
Which of the listed cams suits this combo best?
Any guesses on power output?
What type of tranny was in that van?
Has anyone used an automatic overdrive in a 69 A-Body?