GorillaMaxx single speed conversion is the best setup you can get for a BL conversion. I'm running 3 of them, FLM Emaxx, G2R and one in a UE Lightening. You need to replace the idlers with hardened metal idlers since the stock nylon ones won't cut it - either UE idlers or RCM ones, both will do the job.
The other thing that needs to be done - there is a hollow spring pin in the output shaft that must be replaced with something solid. I used a piece of L wrench, some use piece of the shank of a drill bit. The hollow spring pin will shear off as soon as the idlers are replaced. Its a mess to fix once its sheared, so do it before when its as easy as driving out.
The other weak point is the slipper. I'll try to find the link on the how to upgrade to the 3.3 style slipper which is far superior. The next best thing is the RRP dbl disc unit. The stock unit, even with 12 pegs in the 12 holes will slip and melt. You'll prob need to use a metal spur too - plastic ones have prob melting. The RRP dbl disk unit is not bad used with metal spur. The 3.3 unit is hard to gear due to the limited choices of spurs that will fit.
Here's the single speed conversion -G1 single speed
http://www.gorillamaxx.com/
Its shown as out of stock - check RC Monster, they sell it as well, seems its out stock there as well. Send RCMonster Mike an email and ask if he can get one for you. Ask him about the idlers as well. RCM is a great place to get the stuff you'll be needing. My single speeds have come from there an my CC 2200 combo as well, alonmg with a ton of other ancillary stuff.....