Interestingly enough, all the internal passages of the block are the same size as the early squirt blocks with the 3/8" pipe threaded ports.

My 95 truck had a 96 squirt block (early 506) and it had the 3/8 ports.

As soon as you go into the block past the fitting, the passages are the same as the early ones.

The cooler bypass and the filter bypass are the same on all the blocks as are the inner passage plugs.

The whole cooler plumbing change is a bit of an enigma, as the block is still the narrow point.

I have seen several of the late blocks hooked up with the early coolers and using the early style lines with no ill effects.

If you have the option to use a cooler with larger ports, I would do it.

My fresh AMG Block for the DaHooooley is getting the early lines and fittings as I already bought new ones prior to getting the late block.

I am thinking that in very cold climates where the oil can get like MUD, that the larger cooler/lines would be better.

I ran a high cap oil pump on a none squirt block for a year with no apparent adverse effects. Just makes a BUTTLOAD of oil pressure.

80 PSI down the road and Idles at 40 hot.

Other than in Cold weather, it was great. In low temps the pressure would peg the gauge.

IMHO in a moderate climate, I would not worry at all.