Max Ink Density in PDF output question

HI there, any help is greatly appreciated. I have been wrestling with this for quite awhile now.

I’m preparing an ad for print. I am assembling the ad in photoshop CS2, CMYK 300dpi.

In the Spec sheet I received from the Magazine, it contains the following instructions regarding the proof that must be submitted along with the ad.

‘Proofs MUST be created with SWOP Web Offset gains. Publication not responsible for variance between digital file, and any proof not listed above. Proof must be screened at 133 line screen on publication base, color calibration SWOP Standards, Density max 260%-280%. ‘

In a previous ad I did they said that the ink Density was too high, I had attempted to correct this by Choosing Edit>Convert to Profile, picked Custom CMYK and entered 280% in the Total Ink Limit box. This appeared to correct the problem, as when I checked with the eyedropper, all the Total ink densities has gone down to under 280% (where previously they had been closer to 300). It seems though, when I print the ad to Acrobat 7.0 the resulting PDF ends up back at 300% max.

If anyone can point me to where I can adjust this output (either in photoshop or acrobat) I would be greatly appreciative.

thanks,
James

PS Here’s the rest of the spec in case it helps:

Format:
Hi-res PDF files (made ONLY through Acrobat Distiller) No native application files accepted. PDF files MUST be made using Acrobat Distiller 5.0 (preferred) and also 4.0 (3.0 will NOT be accepted)
The Hi-res PDF distilled files must have:
1. All fonts embedded (NO True Type fonts accepted)
2. The correct mode (ie. CMYK or Grayscale). Never RGB or LAB or embedded color profiles.
3. All spot colors MUST be converted to CMYK unless running 1, 2, or 3 color ads. NO file with PMS colors accepted unless pre-ordered.
4. OPI must NEVER be included in the file. (see advanced tab in distiller)
5. Resolution: 300 DPI for all submitted images and files.
6. All ads must have position marks for non-bleed ads and trim and bleed marks for bleed ads. The Following are the ONLY ACCEPTED PROOFS for (4 color ads):
1. Kodak APPROVAL Proof
2. Matchprint DIGITAL H/T Proof
3. Fuji FINALPROOF
Only B/W ads can be submitted with contone proof.

THE CORRECT SIZE PROOF MUST ALWAYS BE GENERATED DIRECTLY FROM THE DISK/FILE YOU SUBMIT.

Proofs MUST be created with SWOP Web Offset gains. Publication not responsible for variance between digital file, and any proof not listed above. Proof must be screened at 133 line screen on publication base, color calibration SWOP Standards, Density max 260%-280%.