If you want to use both of those models, your list will be not too competitive since Bloodcrushers aren't the best elite choice, but if you would want to make a list with them you could go for something like this :
HQ:
- Skulltaker
- Bloodthirster
Troops:
- 10 Plaguebearers (objective campers)
- 10 Bloodletters (
ap 3 weapons so good for focussing marines, or other units with a pretty good armour save)
Elites :
- 3 Bloodcrushers (Join Skulltaker with them and give him a juggernaut so his type becomes cavalry aswell)
Fast Attack :
- 20 Flesh Hounds
If you take all this unupgraded you should have around 1000 points (might be a little bit more since I'm not having my codex next to me now). You can always replace the
HQ's if you want, and just take out skulltaker for some upgrades, but I think this is the best way to go since you can use the flesh hounds to force the enemy to fire at them since it's 40 wounds just marching to their face. And meanwhile you can use your bloodletters to take out the most important troops, while using your bloodcrushers to take out the strongest enemies (especialy good with skulltaker because of his Skulls for the skull throne, which forces him to always offer a challenge).
I hope this helped