Oscommerce store customisation

I have identified a number, (about 16), of oScommerce contributions, (led by the multi stores one), to combine to make a store that I want, tighten up security and test for other bugs and functionality issues. I can send you the details of which on request. Your suggestions will be welcomed on a better, more cost-effective way to achieve my goals. These are to be the basis of an Oscommerce store I've developed and now need to improve and tighten up. Regards Felix