A 30mm set with MK103s would be nice but Bk5 has incredible damage if it hits.
From Tony Williams' book:
MG151/20 Mine power 236, MV 700 m/sec, ROF 12 Gun pwr 204, ME 29,400
Mk108 Mine power 580, MV 505 m/sec, ROF 10, Gun pwr 580, ME 42,100
mk103 mine power 990, MV 860 m/sec, ROF 7, Gun pwr 693, ME 122,000
Bk5 Muzzle energy(joules) ME 643,000
-C+