the motor is a volvo B30 car engine that has a marine intake, exhaust and water pump along with marine electrics bolted on it by volvo-penta to then call it an AQ170. the A, B, and C correspond to year of production. A being the first year, B the second, so on.
your machine shop should be able to look everything up as a volvo B30 motor (found in the 240 cars) and they should be able to measure the valves. most likely the machine shop gets the valves from Manley or Ferrea, however they could use Erson. either way, its their job to use their vendors
again, if they cant do it, find a different machine shop.
if you were my customer trying to help me do my job, I would charge you more.
FYI, a complete cylinder head for a B30 is only $250 on ebay or $100 on car-part.com