+1 for Paul Hoyt's advice. Both Aristo and Zone VI cold lights usually drop into the condenser housing with the condensers removed. Your color head will give you diffusion equivalent to the cold light heads, and you can use the magenta and yellow filters to vary contrast with VC B&W papers also. As for the temperature/buckling issues, I haven't used a Beseler color head so I don't know how that will effect your results. If you do get a cold light head, be aware that light output varies with how long the light has been on and that you generally want to turn it on to warm it up a bit before printing. If you can get the later Zone VI version with either the Zone VI stabilizer or the last version with the Zone VI compensating timer then the occasional frustrations of printing with a cold light (varying exposure from test to print or print to print if you're making multiples) just go away. These devices rely on a photo cell built into the head and vary voltage (stabilizer) or time (compensating timer) to keep exposure variation within 1% or so. I routinely made multiple prints with both set ups that matched perfectly in exposure with a wide variety of printing papers.