I'm no Manx speaker - let alone an expert on 18th C pronunciation
Kelly in his grammar (late 18th C) states B as in english bare, a is a broad vowel as in english man, lad, bad, H as english hand , hind E is a small vowel but sometimes long (which I assume is given by ee - one variant of Bahee is Bahie which diphong 'ie' according to Kelly is like as in english crie)

no 'r'that I can hear