351 Head swap

I have a set of the original heads from my '85, had about 550 hrs on them when I changed them out when I built it up for more HP.

If you are going to spend the money on shipping all the way to England I would use a known quality rebuilder.  Jasper Engines is one, or get a new set of heads.  While valve size can give you a slight power increase the Chamber size is important when you swap heads.  If your heads are 70cc chambers you would need to match that or be aware of the changes in compression and maybe fuel quality needed should you swap in say 60cc chambers.  When chamber size is decreased compression goes up.  That can certainly help power but you need to know what you have and where you want to go.

Seems the valves are larger on the used head I bought (casting number C90E) , and so I would need to have it machined to accept my old valves from the cracked FOJE to avoid having one bank run leaner than the other.
The valve stem is different length as well, as is the adjustment method. C90E has manual adjustment, and FOJE is hydraulic, so I'm not sure its actually possible to swap the valves.

Also found a small crack in the other existing heads water jacket, so its starting to make more sense to just get a pair of Reman heads instead of trying to bodge what I have.

Anyone bought from these people before, and know if these heads are compatible?

https://www.ebay.com/itm/172431585501

Or suggest an alternative?

Thanks

GottaSki wrote: Totally different rocker  system on those two heads.

I replaced my GT40 heads with GR40P heads on my previous ('96).  I don't know if your heads have the same hydraulic lifters, but if so, I wrote down the whole process step-by-step, including valve adjustements.  If you go that route, happy to send info.

Not knowing what you have for an engine, maybe the standard carbureted 240 or so HP engine, the head in the Ebay ad will bolt up to your engine. And it's not a gt40 head like the seller says

Hi, I have snapped 3 plugs trying to get them out of a head that has a small crack in the water jacket, which occured and was welded before my ownership (last 17 years).
The crack has always weeped since I've owned it, but has been getting worse last few years. Plugs are probably 5 years old, and have rusted through.
I think at this point I'm better off replacing the head, rather than trying to get the broken plugs out and deal with the crack.

Does anyone know if this used 1969 C90E 351 head would be compatible with my 1993 351?
https://www.ebay.co.uk/itm/224503400785

Is it as straightforward as installing with new bolts and gaskets, or is there checking/ measuring of the valves etc I would have to do?

I'm in the uk, so heads are not as easy to find. Not really interested in performance upgrades, just want to get the boat operational again. Has approx 1500 hours on it, with what I believe is all original engine.