My conversion I have been working on for the last couple years is a 1976 bay. I got a solid body out of Wyoming with a failing motor for $3000 turned around and sold the motor for $800. It came in a deep metallic purple. I kind of like it. I bought the straight 100 V hyper 9 kit from EV West with 5 Tesla batteries. I have 40 to 50 miles of usable range and mostly run around town avoiding the highway although I did take it up to 85 MPH once. I have to admit I like the attention which I get a lot.
A couple things that may be unique to my project which you may or may not want to copy.
1.) I stuffed the 5 batteries where the fuel tank went. On the plus side, this saved space on the interior, kept the HV wires very short, the total mass and CG is almost exactly like a stock bus. On the down side, things are tight to work on.
2.) I built a metal box around the motor. I did that for a 3 reasons. I wanted to create space to mount the controller and charger in the engine compartment, I wanted the ability to harvest the waste heat off the motor and controller to help keep the cab warm and I wanted to keep dust and water out as much as possible. I figure there should be 2000 Watts of waste heat available under normal operation. I have made provisions for 2 3" ducts to circulate the air from the engine compartment to the cab. I have not completed this portion, but if I did I would block the intake air vents to keep the heat in during the winter and install a in line duct fan to move the heat into the cab. I initially had some almost overheating problems from lack of air flow, but I just made a larger air relief below the motor and plugged the future vent holes. While driving the fresh air is forced through the normal intakes up high and past the motor at a high velocity. This keeps thinks cleaner as opposed to dust and splashes from the road getting into the engine compartment. I also am using the controller cooling kit and recently moved the fans so they blow air in the same direction as the air flow. This is all working very well.
3.) I cut a hole in the roof and installed a removable 100W solar panel. This keeps my larger 12 volt deep cycle battery charged. I have a 1500 Watt inverter to run whatever. I purchased and set the DC/DC converter, but I have never needed it due to the solar panel set up. Every watt counts I figure.
As far as future work, I would love more traction battery power of course. I have played around with modifying Tesla 3 batteries which would fit if I I installed them stacked and allowed them to protrude between the walkway. I also started a thread to build a trailer with batteries.
I have also played around with concepts for a full solar roof. With current tech I figure I could get 10 miles per day on full solar.
Since I have already spent too much money I think I will just hold out for a couple years until battery prices and specifications improve.
I am currently struggling installing my ZEVA BMS. I accidentally pulled some of the cell monitoring wires off the Tesla S modules. I am dreading taking apart my battery pack and not exactly sure how to reconnect the wires to the aluminum plate. ( I don't have an ultrasonic welder)
I am in Utah so heat is an issue. I have played around with installing a 160 CC natural gas powered generator and using the waste heat to warm the cabin. I would also like to install a heat pump AC unit.
If you have any questions or are working on similar upgrades on a bus I would love to hear from you.