Hi Invectivus, sorry to hear that your machine shop flaked out on you
. Here are the specs for a stock 200 short block for a bit of comparison and it was a very decent combo in its day.
This is for an early 1965 to 1968 200 7 main stock short block.
3.680 Bore Size
3.126 Stroke
1.511 Piston Compression Height
6.5 CC's Piston Dish
.019 Deck Height (Down the hole)
.022 Thickness for the original Ford steel shim head gasket
.041 Quench Distance
3.810 Aprox. Ford Gasket Bore Diameter
52 CC's Chamber on stock Ford Head.
8.7 to 1 stock Compression Ratio
All specs above except for now a
62 CC's Combustion Chamber 1970's Log Head Swapped on using a FelPro composite head gasket
.050 Crush Thickness of the Head Gasket
.069 Quench Distance
7.71 to 1 Compression Ratio
From this we find the CR drops 1 full ratio point from what the early stock 200 six was and would be a significant loss of horse power and some torque too.
Some other items to note there was another set of stock cast Pistons that Ford used on some of the California Emissions 200 six'es that had a 10 CC's Dish Volume and plus there were the 250 Pistion's which had a 13 CC's Dish Volume. Note that most of replacement Pistions are only a 1.50 Compression Height droping the piston down the bore to .030 so the blocks deck should have a cleanup cut on the deck surface to square it up and reduce this deck height without this the NA engines compression ratio will be considerably less than original stock 200 engine. What is your goal compression ratio and do you know what the piston dish volume and compression height of your Pistons is?
A Typical Stock 200 Rebuilt Short Block's Specs
3.710 Bore Size (.030 over bore)
3.126 Stroke
1.50 Pistion Compression Height
6.5 CC's Piston Dish
.030 Deck Height (if the block is has not been decked / milled)
.050 FelPro Head Gasket
3.810 Gasket Bore Size.
62 CC's Combustion Chamber with A 1970's Log Head Swapped on
.080 Quench Distance
7.66 to 1 Compression Ratio
203 Cubic Inches
Using the 1969 to 1983 200 or 250 Log Head milled to a 52 CC head volume brings the compression ratio up to 8.69 to going to 50 CC chamber you get 8.78 slightly more than stock, using a .044 thick Victor head gasket brings the CR to 8.91 to 1 and still might be okay. The bad thing is that the Quench Distance needs to be in the .035 to .050 range for best results with a Zero decked block and a FelPro head gasket its at .050 or better yet .044 when you use a Victor head gasket. You can even have the pistion + .010 or more above the block then you could use a 9.0 to 9.2 to 1 CR depending on your location and still use 87 pump gas.
You can ball park the mill cut by using a .010 cut for every 2 CC of combustion chamber reduction and be real close, still it's better to CC the head if possable. So if you have a starting 62 CC chamber now then roughly a .050 cut will bring your head CC's down to 52 CC. Another .028 mill will compensate for the differance in head gasket thickness for the Felpro head gasket. But I am assuming that the block hasn't been milled any or zero decked to compensate for that extra .011 the pistons are down the hole. Additionally if your head dosnt already have atleast a 1 3/4 inch carb mounting hole opening its a good do it now so you can use some of the better late model carb's if you want in the future. Better yet is to go to a 2 to 2 1/8 inch carb base hole and radius the bottom edges of the carb hole leading into the Log for either size holes is worth a little power. The 2 to 2 1/8 inch hole will make it easy if you want to use a 2V to 1V carb adapter. Have a good good 3 angle valve job done with a 30 degree back cut on the intake valves and a back cut on top edge of the exhaust valves is also good idea. Also consider doing some valve bowl porting / cleanup and a center exhaust port divider. Hope that helps you some in figuring it all out, best of luck on your 200 build up