check NADA.com for the price
Since you stated plural engines and drives, then I assume you are looking at the 30'er.
Looks like $22k with stock 330hp power and up to $33k with 450hp engines. However, be careful of that $33k number as it assume an 502 engine which is worth more (think resale...) than the 454's. Maybe $25 would be a good offer, but paying more than $30k would put you at risk of being upside down.
Also, having the engines reworked after only 120hours (hull hrs-engine hours) would need an explaination. Since you are saying they are 450hp, they are not stock Merc units. I'd require a detailed list of parts used to build them up, name and contact info for the engine builder, then I'd call around and find out if the engine builder was good or not. A compression test would be nice insurance also.
You've got a $11k NADA range riding on the performance and quality of those engines...so do your homework on them!