Big Block Advice Needed

Half a second quicker is going be a big ask with 9:1 CR.
I would at least check or measure the current cam so that you have a starting point.
You say it has the largest FT cam that Comp has. The engine should have a very rough idle & a high idle speed. The largest HFT cam in my Comp catalog is 320* adv, 268 @ 050. Could not imagine that would be very streetable & going bigger might produce diminishing returns.

Here is a warning in the Erson cams catalog. It only appears in the Mopar 440 section, no other brands. Hmm:
'...beware of too much duration [ with TF transmission ]. Although the longer duration cam will make more HP, the loss of tq at low rpm will more than offset the gain at the top end & the ET will suffer.'

This is because of the high rod/stroke ratio of the 440.