200 Deck Height

I just got finished checking my deck height on my 200. I cleaned the deck surface and the piston tops and this is what I came up with starting with #1:

0.012 0.017 0.010 0.018 0.014 0.018

Should I just deck to the lowest or is there a set height that is preferred?

You need your machine shop to make sure the deck is parallel to the main bearing bore.
Then measure the rod length & the piston pin to crown height.
Need to find out why the variance with your present deck measurement, before you start decking the block.
There is a problem somewhere.

I'm debating weather this is even worth salvaging... The bores measured front to back are 3.6785" (all 6). The bores side to side go from 3.6770 to 3.6790. So a smaller bore than advertised. Kind of strange because there is a ridge in the bore. I measured just below that and got a low of 3.684" and a high of 3.696" So in theory a 0.020" overbore, align hone and block deck should clean it up.... BUUUUTTTT... With a varying deck height and wonky cylinder bores... I'm wondering should I.

What are you using to measure the bores? They should not be/aren't less than 3.68". Variance in the deck height could be user error measuring from the side of the piston and not the center, rod length variance, mismatched bearings, replacement pistons here or there, i don't know. It's not consistent from one end to the other. Which points to something other than parallelism. The bores being egg'd would not be surprising in an old motor, but they won't be less than 3.68" in any direction.

I have a cylinder bore gauge. Measure 3.680" on a micrometer, then set zero on the gauge. Put it in the bore and take a few measurements. Built a few old engines, but never had one vary like this. I have no idea why the bore is smaller than advertised, but it is. I checked a few times. Went back to the micrometer to test my zero and then checked the bore again. I want to keep the 200 in my Bronco, so I think I'll call around to machine shops tomorrow to see who can fix it up.

The inconsistencies of the deck height is really quite normal given the acceptable tolerances of 30-40 years ago when these engines were made. Don't fool yourself into thinking that the Big 3 spent any effort in the non-performance engines like they would have the Boss 302's or 427's of the same time period. Today, they would likely be much closer with CNC production manufacturing being used in this industry.