Head gasket compatibility b28 vs b30

[frogish]

So, last week my car ran hot. Managed to find a spot to stop the car along the road and immediately after I turned it off water started to spray out from the reservoir.
I was a hair below the red area on my temp gauge.

I've done a compression test, showing 125psi (rear) to 135 psi (front) and the ones in between about 130 psi. I have no "milk" on my oil stick or under the filler cap. She starts up like before.
However, I did a test with a CO2 tester in the coolant reservoir and the testing liquid turned yellow = exhaust is escaping in to the cooling system.

So I have a blown gasket, a warped head or a cracked head. Or all three. Now comes my question!

I'm trying to find a gasket here in Sweden. I have a 2800Cs - 69. However all the shops stock the b30 and b35 gaskets because that's the engine the go-fast guys use.
I can order a b25/b28 gasket from W&N for 67 + 19 euro, or buy a b30 gasket in sweden for 37 euro.

But will it work with it?

 

[frogish]

Well I just realized that the bores are larger in the b30, so I will lose compression.

Does anyone have the same experience with "good" compression and leakage to the reservoir? Was it your gasket or cracked/warped head?
I've read the forum that the 83-88 heads are best and will source one of those if the head is toast.

 

[sfdon]

Sounds like a cracked head.

 

[Honolulu]

You'll have to take off the head to know the damage, and once you do that you'll require another head gasket. Getting another cylinder head (and reconditioning it, if used) will take some time. You won't need another gasket until some cylinder head is ready to be installed; you can get the gasket in parallel with doing or having the head work done.