My setup is FE motor, so none of my part numbers are the same. But I have experimented with both types of slave. I used the ERA master and slave and small spline fork and McLeod T/O bearing on my toploader.
When I changed to the TKO 600 I went with McLeod concentric. Mainly because the new alum block didn't have a through hole for the slave bracket and I didn't feel like drilling and tapping. The TKO with the Ford front end has the same diameter bearing retainer as a toploader, so the same T/O bearing should work. The clutch doesn't care how it gets pressed
Easiest thing you can do is call Doug at ERA and run all this by him. He has done it all.
One thing he will tell you is whether or not to use the McLeod 5/8" spacer between the TKO and the Lakewood. If you have the long input TKO, you have to use it, I think. If you have a short input TKO, you don't need it - BUT - your tranny may not line up with the mount holes in the chassis. ERA's design assumption is "long input TKO and spacer." Use the McLeod spacer, not a clone. The Mcleod has clearance for the hydraulic fittings on the slave cylinder.
If you choose the McLeod concentric slave, the ERA/BMW stock master cylinder will have to be upgraded to a Tilton 3/4". The stock one does not provide enough volume for the McLeod slave. This is per McLeod, also. You can get this thing from ERA or Summit/Jegs. You will have to cut the steel line a couple inches above the BMW cylinder. The Tilton uses a short rubber hose as a connection as opposed to plugging the flared steel line into the master cylinder socket.
The Lakewood bellhousing needs to be centered. Buy a cheap dial indicator with magnetic base. Summit has one. The reason you must do this is the crank centerline varies when the main journals are align bored. My FE was off .027". McLeod and Tremec both spec the variaton at .005". Since the adjustible alignment pins only go up to .021" I had to open the holes up and use the weld on collars and the long pins.
Just some lessons learned over the last few months ...
Sam