A [precious] few of the early heads have a "300" cast on them somewhere - even fewer (earlier) versions have it stamped in the area in the center of where the cam bearings fit. The K7/8 heads have a "392" cast on the center top fin at the back of the head. The ones showing a "410" there are the F2/3 heads. The latter also have larger intake valves and the rear side fins are notched open where the cylinder studs go thru. For all practical purposes, the F0/1 heads are the same as the 392 versions, but may lack the casting number on the center top fin.
The cylinders come in 3 types (not counting the +1mm taller versions of the late K4 that were made for 'improved MPG' advertising purposes):
1. the K0-K2 early versions, which have the smaller stud holes with no seal recesses for the 8 inner studs.
2. the later K3 thru K6 versions, which have the larger 8 stud recesses on the inner stud holes, for the special 8 rubber dowels.
3. the F2/3 type, which are notched open for some of the rear studs to pass outside the fins on their way down to the cases.
The first 2 types can be swapped without issue, so long as the seals & dowels (or lack thereof) are observed.
The F2/3 type require changes in the head studs' washers to make them seal inside the head so they don't weep oil when running hot.
If you want to "find" one of the taller ones you have to install them onto a case with crank and at least 1 rod and a flat-top piston, then turn the engine to its TDC to see if the top of the piston stops 1mm short of the top of the bore. They are pretty rare.
There are 4 different types of cranks, ranging from the lightest K0 versions thru the heaviest ones in the K5/6. I've successfully swapped them all regardless of the flyweights, though, even putting a used F2 crank into a K0 once. The K4 onward are better machined overall.
The cams: outside of the engine, the only way to tell which era they came from is to set them in a head with a dial indicator (and having the cam sprocket on will help) to note when the intake lobe raises 0.004" from the back of the lobe as it is rotated. If it opens before TDC it is a K0-K6 type cam. If it opens at TDC it is the later one. The 410 and 392 cams only vary in the closing ramp of the intake valve (steeper on the K7/8), so those can be harder to sort out. I've not seen evidence of the "increased lift" of the 410 cams in the ones I have measured (or have on hand) - they were shown in the manuals as having a full 8mm [intake] lift, but I've never seen one that actually did: they were all the same 7.8-7.9mm lift as the other cams.
