........................I mainly wanted to get the engine details and suspension details correct for this era, or a little later (81, 82). I will be using an AMT NASCAR donor kit/engine so I need to back date it/modify it severely from the 90s.
Narrowing down the years helps us to help you...which is all good
The NASCAR donor kit will yield quite a lot.....
It seems like you are wanting to build something from '78 thru '82 which will yield you the most possibilities as there was quite a bit of radical change with in those 5 years.
Engine details....keeping in mind a NASCAR donor kit, I recommend a MOROSO air cleaner and Holley 4150 Series type carb. Keep in mind what I said about the sump system..it can be either dry or wet. Get a set of oil breathers and you will be set. If you desire, a prewired distributor will enhance it.
Suspension...again its what you desire....front and rear...ditch the NASCAR rear suspension and find a quick change and some leafs unless you build something closer to '82 in which 4 links where quickly becoming the hot set up.
Up front, you could run the NASCAR set up which would date it closer to '78 unless you ditch the weight jacks and coil springs and go with a coil over set up which would have started to show up more in '79 and later. Keep in mind what I said about manual rack and pinions being used in 1979.
Steel wheels , as pictured til about '80-'81 then Aluminum wheels. There where Aluminum wheels before 1980...they would look like the wheels on the Starsky & Hutch Ford Gran Torino for reference.
Chassis seemed to change virtually overnight. For something from '78 -'79 you could take the front frame stub from any 70's Camaro/Firebird and attach it to the NASCAR donor frame/chassis. In 1981 Dillon introduced the first offset frame/chassis/cage for asphalt racing...the Mark II.... and it was very soon after that this design made its way into the dirt ranks. You could convert the NASCAR donor to an offset with a little work.
Don't shy away from the Gator bodies.....he's raced the dirt himself and his bodies are some of the best dirt bodies that I have seen.....I have a few myself and look forward to when I can get started on using one for a dirt build.