Not sure why you say that the usual lead from East would be a heart. Determining the most likely lead requires more than knowing the 4 hands: it requires knowing the auction, since, as Reese famously wrote, there are no blind leads, only deaf leaders.
In any event the normal lead against a suit grand is trump. This is because one can usually safely assume (so long as one does not hold a stiff or something like Jxxx), the opps don't have a trump loser/guess, and because any other lead risks picking off a position or eliminating a guess or simply giving up a tempo. It's not as if we rate to have an immediate winner, unless we have reason to believe that maybe they've gone off the rails (as happened famously in a LM pairs event not so long ago).
We need the grand to be at least 50% for it to be a good contract. Make it, and get a tied for top (possibly a cold top): go down and we have at most a tie for a bottom.
On a trump lead, win in North, cash the heart cross to the diamond 10, finding out the break.
Let's assume 3-2 (68.5%).
Ruff a heart high, and return to hand with a trump, pulling the last one.
Cash the heart K.
If the Queen has appeared, we are almost home: we only need 4 club tricks (4 trump, 3 hearts, a heart ruff, 4 clubs and the spade Ace) So we'd play on clubs, making on all 3-3 or 4-2 breaks and the stiff Jack and the virtually impossible 6-0 onside.
Assume the Queen has not appeared.
Play 3 rounds of clubs: if the club jack drops (but not, yet, if it is stiff), we have 5 clubs and make. If not, ruff the club.
Unfortunately, you cannot inflict a squeeze in this position, since the squeeze card is that good club, and you don't have communication. You are down to AQ void void 10 opposite xx J void void, and are in your hand (not that it matters: it is even worse if you are in dummy!)
You don't have any choice but the spade hook.
This isn't a bad line: if trump are 4-1, you have fewer options, since you can't ruff a heart in dummy and a club in hand, without promoting a trump winner for the defence. But you still make if the clubs come home, which is a pretty good shot...all the 3-3 breaks (a priori 35.5% but less once trump are known to be 4-1) and one third of the 4-2 breaks and of course the spade hook.
Plus if the heart Queen drops, you have 4 hearts, 4 trump, 3 top clubs and the spade AQ. You may have a show-up squeeze on LHO (if he holds Jxxx in clubs and the spade K). How likely that is depends on who has the 4 trump...if East, pretty good chance, if West, very poor chance.
I couldn't calculate these odds at the table, but I think that they are probably, in aggregate, over 50%. Plus this is the sort of hand I enjoy playing at the table. So I'd personally want to be there, but doubt that I could.
2C 2S where 2S is a balanced 8-11 hcp
3C natural
3H This is where the problem arises. 3D shows a 5332 hand with 5 diamonds. So that is out: 3H shows 4 hearts
Now opener knows that we are in the slam zone and the question is whether to bid 4D. Seeing the hands, this is obvious, and now South, with the great diamonds, in context, and the wonderful club K, will surely cooperate and grand may be reached. However, these auctions are always easy when one knows the hands. At the table, North may elect to invite slam (4N over 3H, lest responder have an unsuitable minimum) or pick a slam 5N, or blast a slam (6N)). I wouldn't expect the first, overly pessimistic choice, but either of the other two work. 5N is interesting, since South might choose 6D, showing a reasonable 4 card suit, and North could choose to raise.
Edit: I am not claiming my suggested line is best, but I always try to answer play problems in about the time I'd have at the table. Now, it took me a lot longer to write this than to formulate the line, but I suspect that I'm going to need to play the companion boards this round very quickly
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari