Here's some charts that helped me decide:

https://www.speedwaymotors.com/image...lovermount.gif

https://www.speedwaymotors.com/image...2553243A-R.gif

And then I phoned and talked to a tech rep and we decided on a 300# spring for my Model A with a rear 20Gallon tank, battery in the rear, and no back seat. Also a SBC motor in the front.

Sean