What type of studs/bolts/allens would you recommend?

I agree. Grade 5 is plenty. I went the with the all thread from fastenall. Got a 3 foot piece for $3.50 and used blue locktite on the engine side and still double nutted everything. Nothing has broke, stripped or come loose.
Evan

yes I agree with all the grade 5 bolts recommendations ,

I constantly experiment with different bolt heads sizes and grades all the time and i did have a lot of trouble with bolts vibrating loose, snapping off etc... I would recommend buying some cheap CALIPERS and measuring your bolt lengths, although i have accidentally gotten the wrong length bolt and spaced it out with some stacked washers. I've played with the calipers with washer stacking too.

If you measure the bolts, you are free to be able to take them out, measure the cheap brittle one and then put it back in and go to the store. And buy 2, heck buy 10 or 20 at the hardware store.

Calipers are pretty awesome once you get to using them on things. you'll start to see how varying the sizes of the same pieces can be kit to kit. you can see what your favorite and most durable pieces measured out to be and stop putting the thinnest weakest loosest stuff back on your bike.