My Endurance 35 was built by Belluire and is Ketch
rigged and doesn't have much weather helm if the sails
are trimmed right. My main mast is stepped so that the compression
post is just forward of the aft bulkhead in the head/shower area. Mine doesn't exhibit any excess weather helm if the sails
are trimmed and reefed properly for the conditions, and I've had her in 35kts before.
If your's is a cutter
try putting a reef in the main early and keeping a larger head
sail rolled out fully so you have the same sail area but just placed father forward. This would help you eliminate that weather helm if you feel there is a problem. Also, if your main has a large roach then that could help induce weather helm as well.
If it was me, I'd put the mast where the designer wanted it to be, but if it was moved already then all the rigging
was probably sized for the current
location so that it could get expensive if you're not already replacing the rigging
But as far as inherent weather helm, at least in a ketch
rigged Endurance 35, it is not any more noticeable than my previous Cape Dory sloop