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.
SY Wilna Grace