Adding HVAC/Windows in landmarked building

I am adding an HVAC system and changing windows in my apartment with a general contractor. It is a small project, but we live in a landmarked building. I am looking for an architect to do a side-project for a flat fee. The renovations meet the qualifications for an expedited review (10 days) and the LPC needs some basic drawings to demonstrate what we are doing. The windows are internal facing (non facade). How much would the fee be for something like this? Does anyone know of any firms that only do work like this? I really don't need an expeditor (we need it done in the next 3-4 months) but just want to get this processing rolling ASAP.