Drawbacks to rough idle?

A tighter LSA on a 260 cam will not even be noticable.
I had a 260 Comp in a 302, 110 LSA... You couldn't even hear it. Sounded stock. Moving the LSA down to 106 or 8 would not be an issue at all.
The LSA does affect idle, but not nearly as much as duration. I am surprised a cam rep even made that remark while discussing a 260 cam.
Another thing to note:
LSA & duration affect idle, but also the choice of single or dual pattern cam affects the idle.
A single pattern cam has a very rythmic lope, assuming enough duration to lope.
A dual pattern cam has a very rough, chaotic lope.
Personally, I would not use a Comp 260 ever again... At least not the 'off the shelf' version. A tighter LSA version might be better, but only in a very mild, daily driver, little to no mod type of car.
It would be great in a truck though.
My .02
Dave

I agree, the cam works very well for what it's intended for, which is low end torque, but for all-around performance, Comp makes better cams. I'd try at least a 268H which is a very, very good street grind, has a nice lopey idle, and will produce more power and increase mileage. Now what more could you ask?

A park plug or two will need to be changed a little sooner, but it is worth it!

HistoricMustang
www.historicmustang.com

This is the cam in question.

I would run this part #31-412-4, this is one of my specialty cams. It
is kind of a small cam with a tight seperation, which will provide torque and
the sound you are looking for. Here is the spec card for that cam.
Cam Spec Card Inquiry
PART NO. 31-412-4
01 INTAKE MASTER 260H-9
02 EXHAUST MASTER 268H-9
03 ENGINE FS 260AH-8
04 GRIND NUMBER FS 260AH-8
INT EXH
05 HYDRAULIC Y/N YES 14 DUR @.050 212 218
INTAKE EXHAUST 15 LOBE LIFT .2960 .2960
06 VALVE ADJUSTMENT HYD HYD 16 ROCKER RATIO .00 .00
07 MAX GROSS VALVE LIFT .474 .474
08 DUR @ .006 TAPPET LIFT 260 268 17 LOBE SEPARATI 108.0
18 ADVANCE 0
09 VALVE TIMING OPEN CLOSE 19 VALVE SPRINGS
@ .006 10 INT 22 58
11 EXH 62 26 DATE SETUP / /
12 THESE SPECS ARE FOR CAM(S) INSTALLED
@ 108.0 INTAKE CENTERLINE

If it is not stupid expensive, I'd say go for it! It has more lift than the usual 260h or 268h. If you plan on changing your intake you will need a bigger cam, but for what you have now listen to the comp tech person.