You would only need to modify your tank a little bit. This board uses a hall effect sensor to count the thread revolutions, rather than use a feedback pot.
As such this system is more flexible, with no pot to wear or get noisy/dirty.
All you will need to do to fit one to your engle tank, is epoxy a couple of magnets (supplied with the board) to the gearwheel which mates with the tanks threaded shaft. Fit the hall sensor to the tanks end plate/bulkhead, and wire in the board to the microswitches already on your tank.
I'd estimate no more than an hours work.
PM me your email, and I'll send you some information and details of these boards. They're made by Markus Rieger in Germany, and cost about 75 euro each.
Andy