LT4 / T56 Super Magnum install into 57 Bel Air Sport Coupe

[FIVE7]

Appreciate any advice on LT4 / T56 Super Magnum install into 57 Bel Air Sport Coupe.

Immediate question: does anyone have experience with this install and know whether the firewall will need to be recessed or modified extensively? Adjustable motor mounts enough?

I've seen pics of LT4 installs in 57's and have also seen myself an LT1 where the firewalls did not appear to have been modified. However, I've heard from a couple of folks that the firewall will need to be recessed. The current firewall is already cleaned up nicely and painted so would prefer not to have the cost to rip it out, purchase a recessed firewall, install, repaint etc. See attached.

The frame, suspension, brakes, metal, body and paint are complete. The GM Connect and Cruise engine/trans is scheduled to ship on 12/29/23 (but has slipped a month since ordering mid November).

I believe I've found solutions to the general items needing attention, such as: fuel pump/tank, engine mounts, cross member, oil pan, power steering pump, exhaust manifolds, but all comments and suggestions are welcome.
And in the event anyone is interested, here are some additional details: I've had the car since 1977 and am doing a nice restomod. The plan is for a fully restored but stock body and interior with big upgrades in suspension and drive train.

Upgrades to date include:

9" Currie with 4:11 gears
Frame has been upgraded with the Summit Racing upgrade kit
Heidts four link
Tubular front control arms (adjustable Heidts coil overs all around)
Sway bars front and back
Everything powder coated black
Wilwood 12" and 13" brakes
Borgeson 600 Power Steering Box
Metal, body and paint work complete (stock Matador Red)
Body on Frame with all new hardware bushings
On order: LT4/T56 Super Magnum Connect and Cruise: Engine 19431955; Controller 19433248; Trans install kit 19329912; Transmission 19352208

Attached is a picture or two - lonely, waiting for it's drivetrain!