Dan
I agree that the 270 raw ProTools files will be essentially unusable. I've done a lot of importing into Sonar from ProTools and it just needs a small amount of attention at the ProTools export stage to save you from wasting a huge amount of time trying to assemble clips manually.
Ask them to lengthen each track so that every one starts at time 0 and finishes at the end of the song, and export each track individually. This will mean adding a lot of silence in many cases, but will mean you can check that all the exported AIF files have exactly the same length.
All these functions are basic to all the DAWs (ProTools, Cubase, Sonar, Logic,...) - it's just the terminology which is different. I've sometimes offered to go and do the export myself, or offer to pay them something if they are being obstructive; it usually shames them into doing it, because it's simple.
Make sure that when you import each track it goes EXACTLY at time 0: I do this by dragging the bounced audio into a new track in the Track View one by one, looking at the indicator near the top of the screen to make sure it's going at time 0. Having Snap on and set to (say) 1/2 will help.
For the effects, you could get close to what you want by having two versions of each of the 8 tracks bounced out of ProTools: one bounced with effects applied (wet), one without (dry). Don't use both together, but you'll then at least be able to tell what sound difference the effect chain has been making, and either keep it (by using the wet version) or try and re-create its effect on the dry version of the track by choosing Sonar plugins that you do have. There's always a way to get close with Sonar X3 Producer, IMHO.