That Rhys Millen "kit" price is out of this world!
Call ARE, Armstrong Race Engineering, and inquire about custom oil pan casting. ARe made all the pans for my old boss when he ran VW SuperVee, US F3, and some late Toyota Atlantic motors.
This was a long time ago before they made a Nissan RWD sr20 oil pan I wanted. They quoted me about $1000/pan with a minimum order of 5. Not bad for a low production casting run.
Oil pump will be the most expensive part and will depend on the design and how many stages you choose to go with. Options are gear, gerotor, roots, and new design Peterson oil pump company makes which resembles a screw supercharger.
For a 4 cylinder engine a 3 stage pump will suffice with 1 pressure section and 2 scavenge.
Due to large volume of oil in the tank, sometimes up to 12qt, you run an inline thermostat that only opens to big loop oil cooler at operating temp.
Drivebelt system would be easy to make. Crank pulley in the genesis is a single rib. Adding an adapter with a cog-belt pulley is easy work. Just need to source a longer crank bolt.
Pump mounting can be done in the A/C compressor location.
Here is a picture of a VW US F3 engine we did with ITB's, drysump, and Electromotive engine control system.:
This is a drysump setup I did on a Nissan SR20DET engine I built years ago: