For fresh water cooled boats. Where are the raw water thru hull fittings located on the bottom of your boats?
On my 1969 27' single engine 350Q, the intake is to the starboard side about halfway from the stringer to the chine, and even with the front of the engine where the impeller pump is. But I don't think it would matter whether it's fresh water cooled or not, you still need outside water whether it goes to the engine or to the heat exchanger.
I have a 67 31 FB Express with twin 350s original were 327Fs. Thru hulls are just outboard and forward of front crankshaft pulley
The fresh water cooled boats came with Groco SVS strainers. On the 31 the intakes and strainers are outboard of the engines. Others are as posted above by Rob
I have a 31 fly bridge sedan with twin 327q that are freshwater cooled. The strainers are outboard the engines about the middle of the exhaust man. with strainers. I have had trouble with air leaks in strainers.
1969 31' they are directly below the strainers (located as Rob listed above...Thru hulls are just outboard and forward of front crankshaft pulley...)
My 31' f/b has the intakes outboard and forward of the engine. It does not appear to have strainers ever attached. Recent inquiry suggests that several members have replaced the forward strainer location with a new inlet at the rear of the engine where it is less congested and, importantly, the shut off valve can be reached if a hose fails. If a hose fails forward of the engine with a hot engine, you would get third degree burns trying to shut the valve.