let's look all of this over........
"Do you think it is possible to drive a 16 pill mobile amp with an A/C tube box?"
as long as you don't exceed the maximum drive input for the type and number of devices used in the 16 transistor amplifier.
"The other thing I have been trying to find out before i drop the hammer is how many watts is an m105c antenna rated at"
it's not the antenna you need to be concerned about, see above.
"The Firebird deadkeys about 250 watts and swings to 350 or 400 watts."
@ 250W you are already exceeding the maximum drive input for the type and number of devices used in the 16 transistor amplifier by 90W.
http://www.firecommunications.com/trdbase/2sc2879.pdf
"I think it calls for 320 amps max. Of course it's a Joker amp so I got the specs from X-Force."
that's because the typical (not maximum) peak current draw for 16X2SC2879's is 320A.
you don't shove 400W into a box with 16X2SC2879's with a combined maximum drive input rating of 160W. that's not class c, it's just bullshit.
class c amplifiers are not designed for am/ssb operation, period.
LINEAR amplifiers (not rf switches) are required for the proper amplification of am/ssb signals and the IMD spec. is just as important as the rest of them.
so hook that firebird up into that 16X2SC2879, blow it up and let's move along. 250, 350 and 400W is way too much drive input for 16X2SC2879's.