Hi Bradley,
It's funny - these seem to be harder to find now than Mk1 and Mk2 Escorts! I guess Escorts have always had a bit of a cult following, but Lasers - particularly the early ones - never really took off. Later ones like the KE and KF/H models had 4WD turbo variants in the TX3s (essentially Mazda Familias with different body work) so more people play with those, but many of the early ones just end up as scrap.
As for the engine choice, I use the car mainly for hillclimbing and compete in the Under 1600cc Improved Production class. I could go bigger but U1600 is the best represented class in the Victorian Hillclimb Championship and very competitive, so I've chosen to stick with it.
The B6D is again basically a Mazda engine (think MX5) but was available in the FWD Ford Capri as I mentioned. From 1985 onwards Lasers moved from the E to B series of engine, so a gearbox from a KC Laser bolts straight up, but most importantly the drive shafts from my car slot straight in making it a much more straightforward conversion.
Do you have any more pic of your Fiesta? I've got a heap more photos and video on my Facebook page if you're interested. 
www.facebook.com/BuzzboxMotorsport