My number is coming up at ERA, options / order advice?

[ERA 778]

I built a 427 a few years ago and tried to do as much as I could myself as well. Mounting the body is a great way to save money and is certainly something you can handle. I did a lot of research on the epoxy and selected GelMagic from System 3 with the slow (summer) hardener to allow lots of time for adjustments. You will just need to get a few friends to help you remove and install the body. (I used 4 or 5 helpers since it goes easier if you have someone to spread the rocker panel areas while dropping the body over the frame. Unless the manual has been updated, it is not very good on describing the mounting process since it reflects the old body design.
While I had the body off, I flipped it over and painted the entire underside with a satin black color.
I agree that the oil cooler is useless for the street. I spent an extra $1000 to install an oil thermostat to keep the oil warm enough on mine! But - it looks fantastic!
Building the rear suspension will also save some money but you might have to get ERA to modify some parts for you. I built mine but ERA supplied all the hardware.
I would definitely spring for the powder coated chassis. Excellent protection and includes coating several other parts. Will make the whole car look more complete and ups the quality of the build.
I also recommend opting for the trunk mounted battery if that is available for the 289. Makes life easier under the hood for access to the engine and for battery swaps.