[Big Dave]

First order of business would be to contact Crower. I’d bet there is some old head in the Engineering Department that knows a thing or two about the Mileage Maker. He will save you a lot of expense and head-scratching. The degree to which the valves are left open will greatly affect the needed nominal combustion ratio.

In essence you are making a Chevy Prius engine. We all know they work. Atkinson engines are efficient but they lack torque. No big deal on a hybrid – the electric motor makes up the difference. You can get it back with displacement or live with less torque.

Since your 350 is blown maybe you should think of raiding a junk yard for a LS-series engine out of a later-model Chevy pickup. I have a 96 Impala (second gen 350) and even for it parts are becoming a bit of a challenge but LS-series parts are easy to come by. Get a 4.8 liter (LR4, LY2, or L20) and try to find a later model 6E80L tranny. More speeds generally equals better MPG. This lets you ditch the hunk of junk 700R4. Get the unified control brain and it becomes plug and play.

Off-roading with a torqueless Atkinson engine will be miserable. You are out of heavy snow country so I’d think about declaring the vehicle a 4x2. Gut the front diff, remove the transfer case (hundreds of pounds and a maintenance problem, plus worth a few bucks recovered for other stuff), put a 4x2 tailshaft on the transmission.

As you mention “class” I assume you are a student and don’t have much money, but something your vehicle affords you (for later on) is an aero option. Your top can be easily removed (and sold). Lay up a “fastback” top (see all the threads on aerolids for pickups. Learn to work ABS and make some fender skirts fore (a la basjoos and aerohead) and aft. Maybe a grille block. An 0.6 Cd is a tough number to fight. I’d bet a 12 degree aerolid, a grille block, and skirt of all four might knock you down to Cd = 0.50.

Even when new, I’d be astonished to hear this vehicle got better than 13 MPG. Lots of scope for improvement and at the end of the day you wind up with a roomy and sturdy vehicle.