Conrods & Heads

[Napier]

Hello all,
I will add a build thread in time, but first I have a couple of questions - I helped my father rebuild a G80 in the late 80's when i was a kid but have done little other than maintain since then, so help would be much appreciated.
I am putting together parts for a 1959 M20 500 (CSR), which was taken apart circa 1984 (broken crank), sold, got mixed up with 2 other 500 engines, also in part (I was advised one of the cranks is good, fingers crossed), and then reacquired 40 years later still in parts.

https://drive.google.com/file/d/1QW17co ... drive_link

1. Conrods
I have 5 off. 2 are clearly a pair, based on their shape and part number location. Having read the year by year changes I take these to be earlier rods as they have less material on the small end. The other three are odd in that the part numbers are in different locations, but the shape appears to be the same. Is there any issue mixing these up, and if not, is there any considerations when picking 2 of the three to use? I assume I want to use later rods as they will give us the correct weight to counterbalance the later crack which has wider and what appear to be slightly heavier counterweights?

https://drive.google.com/file/d/136rGTA ... drive_link

2. Heads
I have 3 pair of heads. 1 pair appear to be pre 54 (4 bolt covers), and the other 2 are the later (correct head). one pair appears to have been cleaned (albeit probably 30+ years ago), with intake manifold studs intact, and valve /lifters/springs disassembled but all parts appear to be present. The other has broken studs, and valve train intact. What should i be looking out for in determining which pair are best to use?

https://drive.google.com/file/d/1cKkaqD ... drive_link

I am still digging through the boxes to see if i have all the relevant hardware, but starting with the big bits so i can get the engine sent off and then get to work on everything else.

Many thanks in advance for any help

PS, I will get the hang of the images (not uploading or embedding) but for now links is the best i can do.