I ordered all my parts from APE anout 3 weeks ago, now just waiting on them to get here.
As far as the crank goes between a gen 1 and gen 2 your talking about a 2 millimeter longer stroke in standard sizes thats less than an 1/16" thats for the 1441, your 1551 kit has the same crank but the journals are ground to give you I think an additional 2 millimeters. So side by side you could see a difference but just looking at it no you can't tell. The fluted mains are what APE does the Gen 2 (to my knowledge) does not come factory like that.
I had to order the seals and head gasket separate from APE too the 1397 with a gen 2 crank does not come with any seals, gaskets or bearings other than the piston rings. Its an extra $200 for all the seals and gaskets. You have to order the main bearings yourself from suzuki based on your crank and casing specs they are about $9 each you need a top and bottom, I would have to count I think it has 8 or 10 so another $200 for mains.
If you order cams from APE I think I read the gears are already installed, you may want to check into the, because if M/T just ordered them from APE for you they should have them.