Wow, that is quite some circuit!
I went down the same road at first and finally decided instead to just modify a 94 Camaro wiper motor to fit, I already had a the tilt steering column with the delay wiper switch/ cruise control on the turn signal from the Camaro installed in the Vega.
The GM wiper switch in the Camaro column works with variable resistance and even the high and low speed are not simple on/ off but based on resistance logic as well. I found this out after I had built the 555 timer circuit and relay to pulse the Vega wiper motor... DOH, I should have done a little more research before hand.
Anyways, very nice work on the Monza.
Cheers,
Tim