Is a SEP treated just like any other DC plan for purposes of satisfying the TH minimum allocation?

I have a potential client with a SEP that they've already made a significant contribution to (for this question, let's assume all participants got at least a 5% allocation). They want to put in a DB plan to supplement with the idea of phasing out the SEP and going with a large DB in future years.

In order to fit the combined deduction limit, my DB benefit has to be less than 2%. Am I allowed to say that the SEP is covering the Top Heavy Minimum? I see a lot of things talking about the defined contribution plan, but since this is a SEP, I don't know if that's included.

Thanks!

Here are a couple of ideas:

1. Limit the owner's projected benefit for the first year, so that all others can get the 2% TH min in the DB
2. Check the new deduction limitations now in effect under PPA. Did the SEP contribution exceed 6% of covered payroll? If so, then the db can still be funded to the minimum deduction level, but you might have a non-deductible portion of the SEP. If the SEP did not exceed 6%, then fund a full DB deduction.

Warning: a SEP is not necessarily a DC plan for all purposes, although I believe it fits in the deduction rules.

An attached Q&A blurb confirms the interaction of top-heavy between SEPs and qualified plans (i.e., the top-heavy contribution "may" be provided in the other plan). Therefore, in addition to SoCal's comments I would think the DB plan could be drafted to contain language, if it isn't already in there, that top-heavy will be covered under any DC plan (SEP for this purpose) or added to benefits earned under DB plan to meet top-heavy.

Is their SEP a prototype, or an IRS model SEP? If an IRS model SEP, then contributions to another plan aren't permissible for the same year for which contributions have been made to the SEP.