Nick Mack RDS

It has a 350 hp mack engine in it right now and a eaton fuller 8LL trans 

24 minutes ago, terry said:

No I don't think it would, the R700 hood was about 8 or 10 inches longer, I sure somebody else will post with some info .   terry

Thanks for the info Terry!

12 hours ago, terry said:

Don't think there is near enough room for that cat. engine in a regular R model, the older R700's were used with cat and cummins engines.    terry

Are you saying that the CAT engine would not fit?

I have recently inherited  a 1988 Mack RDS and was wondering what I could do to up its horsepower. The truck is severely underpowered to my liking. I am used to driving a Pete with a 425 CAT. Would it be possible to put a CAT 3406e under the hood of my "88 Mack? I plan on swapping the transmission with an 8LL. Any comments, advise and help would be greatly appreciated. 

edit: I am now thinking a cat C12 would fit better.