Having wrapped my mind around the assurance that we have a 10+ fit (and that partner is less likely than most to hold a 4 card major of either persuasion), I like 4♠. I am not so sure that this is a pure 2-suiter, but I did not splinter with 3♠, so the odds are high.
It is the most dramatic bid I can think of that is not completely unilateral, and so it carries the day for me, with my unusual hand.
A fit showing jump to 4♥, if available, is my second choice but I must confess I did not know of this gadget (and while it is a nice one to have, I doubt that I will ever have a need for it: these are not common scenarios).
A fit showing jump to 3♥ is less attractive: for me it would show a different type of hand, and so partner's next call will be less easy for me to interprete: her bid will be based on expectations of a more classical 3♥ bid.

Help
