OK, there seems to be a bit of misinformation here. This is my two-bobs worth

1. The A10 & 1200 heads will physicly bolt to the A14 block.

2. As far as I know, all the coolant passages in the heads are the same, but there may be some minor variation in shape or size.

3. Neither early or late engine had an oil feed at the front. [where did that front-feed rubbish come from] Both types feed the rocker oil up one of the center head bolts, but the internal drillings that got it there were slightly different from '74 onwards.

4. As best I can tell, you can use an early head on a late block without needing to modify the oiling for the rockers, but not the other way around. I will be using my 1200 GX head on a later A13 block without mods. Make sure that you use the correct, later-type head bolts.

5. The A10 head used round ports, while your A14 used larger oval ports & a different manifold bolt pattern [that the A10 doesn't have]

6. The valve sizes in the A10 head are 35 & 29mm, while the A14 valves are 37 & 30mm
You should have more compression with the A10 head, but it will not make up for any of the other deficiencies.

7. You can have the larger valves fitted, but you will not be able to economicly get the ports to match the A14 ones for airflow.

To summarise.
Use the A10 head, manifold & carb as an emergency, temporary, get-you-going fix if you are desperate to have a running car for a week or so untill you can get the right parts, but otherwise, it's not a good idea.
Your best bet is a good A14/15 head, & if the old one was cooked, then get your cooling system fixed before it happens again.