I did this conversion last Winter. I bought the complete set-up from Raceline as they can supply a more or less turn-key unit including engine, engine mounts, bell housing, clutch, etc.
I went for the compact bell housing to move the engine back a bit - I had Road and Race shorten the input shaft for me while I had the gearbox (Caterham 6 speed) refreshed and upgraded to the latest spec (required to take the power and torque). The Raceline dry sump is great and simple to plumb. I shortened the passenger footwell as that is where I put the dry sump tank - you could buy the (expensive) Caterham one that fits in front of the engine but that's a lot of weight to put up front and makes access around the belts difficult.
All I had to do was bolt the engine in and sort the plumbing and wiring.
The engine was a high specification using Ultimate Performance ported head with 1mm oversize valves, Raceline RLD300 cams, Raceline (Jenvey) 48mm DTHTBs and a Raceco exhaust system. It produced 258bhp on the rollers which is a little under what I expected. Perhaps a less aggressive cam profile would have been better.
If you want the ultimate engine (300bhp+) then the SBD kit would probably be a good bet but you'll need to get someone to build the engine for you as SBD only supply it as a kit of parts.
On track it is noticeably quicker than my old 235bhp K series.