Donar Dilemma

[Trif]

I am at the stage of my build where I have completed my chassis (except engine mounts), stripped my sierra estate (1800 CVH) and I am part way through making the suspension/steering etc (Just machining my mushrooms). Now the sensible advice on the forum seems to lean towards “get it through the IVA with the CVH and then put in something meatier. (which I am doing). However I have just acquired a 2.0 ltr Omega, one owner from new, garaged serviced (with paperwork) 30,000 miles on the clock, really mint. My question is this, Are there any chassis mods that I would be better off doing now, not really concerned about engine mounts more about clearances etc OR should I consider putting the engine and box into the build now as standard and modify the engine post IVA?