In principle, it is ok to use normal PCR instead of qPCR, I see no problem with it (you're going to check the presence of your band on a gel, right?). Should be fine.
I think Yulia Pania is correct. It is no problem to replace qPCR by PCR just to detect the presence of your target protein molecules but might not be quantified, that could be possible by qPCR.
As Effendorf concluded in their following publication might be helpful to check the DNA contaminant in your protein samples "Protein and DNA samples are simply and easily quantified using the Eppendorf BioPhotometer D30. The results are displayed in a clear manner showing all information pertaining to sample quality and quantity. In addition, the optional “Purity Scan” enables assurance of the data by this format of optical control.