1990 SW20 - needs wiper motor and tacho

Hi all,
 
My lovely "stock as a rock" 1990 SW20 has developed two electrical problems:
 
1) wiper intermittent setting she no work - auto electrician says needs replacement 'self park switch' or entire wiper motor (switch apparently is inside or part of motor assembly); and
 
2) tacho not working properly - shows revs about 1/4 of actual engine revs - auto electrician says needs replacement tacho or entire instrument cluster.
 
All advice on replacement parts would be very welcome.
 
Thank you!