what is the oil capacity on a 1978 toyota corolla 1.6

Most everything back in that era used four quarts. Buy five quarts just in case and keep the extra in the truck for topping off.

thank you. would you happen to know anywhere to get aftermarket upgrades for the suspension?

There are no aftermarket suspension upgrades for a thirty five year old car. There's not enough people that would buy them. You might find some generic, universal or racing applications. Find a forum and see if someone has parts on a shelf in the garage.

4.2 quarts with filter

I frequent http://www.toyotanation.com/forum/

I'm thinking of taking an s10 suspension and drivetrain under it. I would only have to shorten the frame 15.3 in and a few other mods to make frame mounts on the body. Put a .4.3 vortex in it and have a badass sleeper