The old 2.0 was the 4G52 engine which was the same block design as the 4G54 engine but smaller bore. It had a different bore and stroke to the G63B engine. You are going to need the G63 stuff from mid 80's to early 90's before the crank went to a 7 bolt design which was used and borrowed all over the place (plenty of FWD cars had them including Hyundai and Kia who used Mitsubishi engines under license) The support for this platform makes it a prime candidate for building boost if turbos are your thing but there is some assing around to convert it to RWD. If you can find the intake off an early Kia Optima, the intake direction can be swapped to forward facing on the 4G63 head. The 4G63 swap has been done on a regular basis and there is s huge amount of info on the process on various sites. As for the 45DCOE's, they are not road car friendly. Only really work when the pedal is mashed to the floor and need a relatively aggressive cam to make them go as well.

My plan was to make a manifold from either a chop and weld approach or see someone about going new school and having a new one prototyped on a 3D printer before being cast in alloy. Bike carbs run rings around DCOE's for all round performance - power delivery, tuning and economy and can be had a lot cheaper than one set of DCOE's but the catch is a custom manifold.