Cadillac 331/365 head code info

Hi

I have recently picked up what I was told were a set of 365 heads for my 331 Caddy rebuild. I am trying to confirm that they are the correct heads before I go to the trouble of having them rebuilt. They have two different codes on them which makes me suspicious and a more than a little concerned!

I have been through the search function, have found some info on the web however have yet to find a definitive answer for both. The fact that there are two quite different codes seems strange to me. Maybe its not - just want to find out.

One head is marked 1462611 & 8N10
The other is marked 1458612-3 & 3N20

Any info you can provide me with would be awesome thanks

 

Come on guys, lots of reads but no info. Surely some of you guys know the answer to my riddle!

 

The 1st set of numbers(1462611) is for a 55 331 head. I have a set on my bench.

 

Thanks 31modelo, from what I have been able to find out that confirms what I thought. I am hoping the second one is for a 365 and I have accidentally been given one 331 and one 365,..

 

Without knowing the exacts of your rebuild on your 49 331, you'll do better with the 55 heads than the 365's.

 

Thanks again 31modelo. I had been told by another HAMBer that the '55 331 heads would be the pick however considering I am in Australia and the lack of parts/options here I thought it would just be easier to track down some 365's.

One year production for '55 v three for the 365's - I figured I would have three times the chances of getting them. Funny after all that I get one '55 head!

I did just find out that the second head appears to be a '52 331 head.

Rebuild will be quite mild, twin or triple carbs, mild cam and a bump on the CR,..just looking for a bit extra than the standard 160HP.

Cheers