Here are the ability score rules used in my current Monday Night game.
Roll 3d6 in order of STR, DEX, CON, INT, WIS, CHA. After that select the PCs Kin keeping in mind the ability score swaps.
Humans can swap any 2 ability scores as desired.
Brownies must swap their lowest rolled score into STR.
Hobbarts must swap STR with DEX or CON if it is higher than either score.
Higgelwyn must swap STR with DEX or CHA if it is higher than either of those.
Petty Dwarfs must swap the lowest roll into CHA.
Stone Dwarfs must swap their highest roll into CON.
Dusk Elves must swap their lowest roll to CON.
Modifiers are similar to the B/X -3 to +3 range differing in having Charisma have the same range of modifiers.
Keeping it simple and restrained while allowing for some perceptible differences between characters based on their kin.
As per my last post we created 4 characters and managed to get two Humans with Strength scores of 5 but with other scores that didn't encourage their swapping any for that STR score. So we ended up with a physically weak Healer and Burglar.