Hi Henry, my searider also usually has a tendency to land portside first at wot. My last engine was mounted dead center, but over the winter I filled the holes and went 38mm to starboard for my new one.
I think it has balanced the boat slightly better but she will still land slightly to port in certain conditions. I guess flat out over nice groundswell occasionally there isn't much in the water except the prop, so the prop is going to heel you over to port.
I have never managed to rid the boat of it, but by raising the engine up has high as it would go seemed to minimise it and when reaching the top of the wave making a very slight kick to starboard means I land square 99% of the time!
Plus for me it only happens at or near wot, I take it in to surf regularly and jumping at lower speeds is fine