For the most part, a Non-Event, unless the differences are very great. To next stop or - we hope, a Mx base, you'll get there, even if one or both have to be tuned back a bit. Once at your Mx base, RAISE HELL, even of one or both engines need a change. Personally, I would not fly it again, without a dual engine change, but we all have slightly different standards. If you do not like it - history or current performance, so not fly it.
That's a truly great airplane and engine combo, but the secondary market may not be paying the attention that they should. Suggesting nothing, the crews on these antiques DO need to be alert for all indicators. Mx at some carriers is sub-standard yet still 'legal,' and seats 0A and 0B ought to know their immediate potential for problems. It the start and run up is a four-minute procedure, give it six. You know the drill and you do want to get home that night or the next.