IMPs. You receive the ♠5 (4th best) as the lead.
Spoiler
Assume opponents will Smith echo if given the opportunity.A) Comment on use of puppet/puppet derivatives here
B) How do you plan on stopping them from running hearts before you take 9 tricks? (Take the chances of blockage into account if you'd like)
C) Does your answer to B change if the auction had gone 1NT-3NT? (Same lead)
Edit: to be clear, I'm not interested in the correct technical line necessarily, but as to what line gives them the least chance of finding a heart switch.