Where would I be able to source parts for it? I would be doing this to an '05 LHD Si in the US. With the engine swap, is it a direct bolt-in? If not, what would I need to get/do for it. It's especially confusing to me as I would think the imported engines are RHD..

 

The steering wheel isn't attached to the engine. From a sensor location/type standpoint... the K20A3 and K20A "R" are very similar. You would use the engine harness from your car and modify it as necessary to fit your K20A engine/trans combination. The obvious change needed would be the reverse lock out solenoid found on the ITR 6-speed transmission since the Si 5-speed doesn't have this.

 

Reverse solenoid isn't necessary; I haven't had mine on my K20A for two years now - reversing instead of getting in 6th gear would be a pretty difficult error, even for me.

Do as much research as you can, even if you're not doing the swap yourself. You'll need Kpro, and dyno tuning afterwards would be very smart to do. At this point, it would probably be cheaper to sell your 05 and import an R, unless you're not talking about a full faux conversion. Speaking of that, what exactly are you looking to swap?