Hi and welcome to the forum. I love strawberry with anything vaping and in life I actually really like all the flavors you have. It depends on how strong you like your flavors to be. If you really want a bold strawberry Capella's sweet strawberry can go up to 5-6% very well. I tend to use it in the 2-4% range that is up to you. Also, the sweet cream TPA is a buttermilk cream it is so good. I like to use it with some of the Bavarian cream which is a nice custard like yolk like cream so these two together in essence can be a start to making your own custard. Since you already have custard you don't have to bother with that but good to know later on.
The vanilla bean gelato is a great flavor that requires steeping before it comes into it's full well rounded flavor which is a bout 3 weeks.
Just by going on your flavors and not really know if you like higher or lower %s I would start out something like this....defiantly change it to your liking since you'll be vaping it.
Sweet SB 4%
Graham cracker 1.25%
Sweet cream 2%
Dx Bavarian cream 2%
Vanilla custard V2 1% ( requires at least a 3 week steep as well )
10.25% overall this one once made would have to steep about 3 weeks ( sit and cure ) b4 being ready to vape.
Just thought it up with the flavors you have there. Good Luck ! If you have more questions come on back and ask away !