Motor swap: '86-5K to '90-100, will it work?

[Mark <mconnor@frontiernet.net>]

Hi.

Does anyone know how interchangeable the 5-cylinder motors between a
1986-Audi 5K and a 1990-Audi 100 are?  The motor on my '86 is presently
laid-up and am looking to replace it with a newer engine.  I have a line
on a 1990 motor out of an Audi-100.  How compatible are the two motors?
The only visual difference I can see is the design of the intake
manifold.  I would imagine that they could be swapped along with the
distributors.  Do you think it might work? Any wiring or ignition
concerns?

Thanks in advance.

Mark