The serial number will contain a prefix either "N" or "S". I'm guessing your gun is an "N" serial numbered gun. If so, N174,000 would be 1973 or 1974.
Originally, your Highway Patrolman was chambered for .357 Magnum and was likely converted by rechambering the cylinder to the Bain & Davis round which is essentially a .44 Magnum case necked down to .357.
This was commonly done in the past, mostly with good results. However, as far as I know, no one has produced factory ammunition for the .357 / .44 and it is a handloading / wildcat round.
If you're lucky, the work was actually done by Bain & Davis themselves. They are still around and can be reached at:
BAIN & DAVIS SPORTING GOODS
307 East Valley Boulevard
San Gabriel, California
Or Contact: [email protected]
With regard to value, I would say that if the gun has actually been done by Bain & Davis then perhaps it may be worth as much as any 28-2 in the same condition, which is to say in the $400-500 range depending upon where you are. If the work was done outside B&D, then the price may well be reduced by the value of a new cylinder which is around $100 more or less.
The above assumes the gun to be otherwise origional and in good, unaltered mechanical condition.