No worries!
There's three ways to do it - use the existing oil pump and just a two-stage external pump (both of these stages 'scavenging' oil from the sump), use the existing oil pump and remove the internals (and use a 3-stage pump, 2 scav and one pressure), or fit a blanking plate over where the oil pump used to be (and use the 3-stage pump), like this: http://www.sbdev.co.uk/Dry_Sump_Systems/Dry_Sump_20L/Dry_Sump_20_norm.gif - it's the item on the right, with the red bung on it.
Yeah, the SBD kit is pretty expensive, but it's the going rate for that engine - and well worth it when you're using the car hard. Obviously the oil is going along the crankshaft to feed the bearings, in a Calibra (where the engine comes form originally) the engine is mounted sideways so it can get oil down the crank no problem, but in a kit car the engine is longitudinal - meaning under hard braking oil struggles to get to the rear of the block, plus you may get some starvation as the pickup can suck fresh air = dead bearings.