Greetings, I am new to Club Hotrod -This is a great site! My name is John Anderson. I am active duty Navy. I was hoping for some advise.

Car: 80 Impala 267, V-8, 3speed auto, previous daily driver 130K miles, very slow acceleration. So far I bought a 305 block and cylinder heads.

The block was supposedly machined and the heads have the springs (new?) on them- that's all that is installed on the heads. The heads have heart shaped combustion chamber and I can look at them again tonight for specific info to any questions.

How do I figure out the cc's for the head combustion chamber and calculate for the maximum compression that I can run on either 87/89 octane gasoline?
Will the crossmember that supports the 3 speed transmission support the 200-4R I wish to replace it with? The crankshaft has the 3.484" throw that stock 305's and 350's use. Is it wise or necessary to replace the stock rods?

I want to use as many parts from the 267 to supplement the 305 as practically possible. I found on the internet that the crankshaft mains are the same large journal size. The motor still has all the smog junk on it. The rear end gear ratio is less than 3 to 1. Honestly, I have never rebuilt a motor before but am sure that I can manage. The goal is reliable transportation, significant torque, low buck assembly, and fuel economy. I am actually not concerned with horse power output. I am willing to spend decent money on a rebuild kit and machine shop work for optimum output. I am strongly leaning towards an RV cam and a 200-4R transmission. Can anyone explain the tow capabilities of a 305, 200-4R, tire size, and 2.X gear ratio combination. I realize that the 4 speed is the weaker version and that the 2.x gear ratio in the differential (10 bolt main) is the worst for general towing. Any recommendations/points of concern are appreciated-especially brand names, or rebuild kits. The small block chevy rebuild kits seem to vary significantly in price. I understand that some kits include rockers, and cams-some don't.
Thankyou all whom respond.