Backwards mounting is not more expensive or complicated to maintain. Pumps are pumps, you'll pay the same cost to buy or repair them, and they're easily available. The motor does not know it is backwards, because hooking to the front of the crankshaft makes no difference mechanically, same forces apply as if the load was hooked to the rear of the crankshaft. The cooling systems for these boats were a "check the box" option at Chris Craft, you could get standard or closed cooling. Therefore if your boat has standard cooling now, you can still find a complete Chris Craft closed cooling system if you shop around. Many of these parts are sitting in shops now on motors that are worn out. It would be easy to hook an aftermarket heat exchanger onto any motor as well, as Mike Burdette did in the photos below, he used Volvo Penta exchangers here.
The engines came out of a 1979 model Catalina. The boat had been repowered in 1993 and had sat for a number of years. They each had about 175 hours on them. The major differences on the SBC seem to be the location of the valve cover bolts (4 down the middle of the cover) and a one piece rear main seal on the newer model engines.
You can not judge a motor by the paint.
Here is Paul Mathias's nice 350Q installation with the Chris Craft closed cooling system on an inboard 23 Lancer. This can be used as a great reference tool for what one should look like. Note the motor is backwards on this application too, and this is a good thing, because getting the flywheel forward takes it out of the zone where it would scoop water and spray it around the engine compartment if you got any water in the bilge. I have that problem with my 20' fiberglass Sea Skiff with the aft mounted flywheel on the 327F motor.
If you decide to install the standard Chris Craft closed cooling, there are probably some people here on The Forum who would either have these parts or know where to get them.