definitely use the DeFever Owners group but here's a very superficial summary.
There are at least 4 models of the 49 Defever so you need to know which one, what year, and if any mods:
The original 49 Raised Pilothouse was made in 2 different yards over the years and usually has the flybridge set forward over the Pilothouse. Most of these models have a mast which may not be hinged but since these are older, well loved, well cruised vessels, many have had these modified, hinged or even removed.
There is another 49 badged as a "49 DeFever" which is known usually as the 49 CPMY. It started life in the first 4 or 5 versions as a "44+5" essentially a DeFever 44 with a 5' cockpit added - so a completely different hull than the 49 RPH with a lower profile. They built a new mold for the subsequent models of the 49 CPMY that are more common. Air Draft for these generally mirror the 44.
Newer, (POCTA built) 49 RPH's have the flybridge set further aft on the Pilothouse. These typically have a hinged radar arch. Air draft with the arch up was almost 23' on mine due to the fixed anchor/steaming light but bimini down/arch folded, you can get down to around 16' +/- for looping.