Many thanks to you all for the rapid response, advice and a clear consensus.   I'll go with 2 coats of the 350.

Great to back aboard an Amel again.  About 15 years ago I bought a SM near Nice and took her to Caribbean and back to the UK during a 3 year sabbatical.  This time I've just retired....  So far, after a month, very pleased with the 54, she has many of the improvements I imagined in my mind whilst living aboard the SM.  

Fair winds and following seas to all.
David
SY Wilna Grace