I've been running my 250 with an Offy 4bbl set up and no heat under it for a year with no problems.
The car is a hot rod so doesn't see daily use year round but I do drive it on a good weekend day in the winter. When I built the engine I did make up a thin cardstock template for an air box around the header tubes in case I needed the heat.
So far that template is only collecting dust in the shop.
