I hate allen and star bolts for engines. I had them on my 1.8t and when i did the timing belt i stripped nearly all of them. Such a pain to try to keep the bit perfectly in place while torquing in all down. I swapped some out for regular hex heads and the rest i replaced. No way I'd ever choose to put them in an engine if i could have normal bolts. Unless maybe in the valve cover, or to hold the carb down, but that's it.
I can get you the lengths of the bolts for a small block, i have a whole set here. Let me know which ones you want.