When I had a cracked block (overuse of block heater on an old 6.9) years ago, I was told the only way to properly weld it was to dismantle the entire block, heat up the block to about 600 F., then weld it and allow it to cool. Then rebore, etc. the block. Ended up getting a used motor and having it rebuilt.
Early 99 F350 4X4 CC 7.3 Auto. A.R.E. Topper, bed carpet/bench inserts, Rhino grill guard, AIS w/sleeve, Fuel filler mod, GOS headlight harness, 02-04 Headlights, Rancho HD stabilizer, 06 Telescoping/heated mirrors with C-Btr Mirrors, Hella FF1000, Htr Bypass valve, front receiver hitch, Quadzilla XZT gauges, ITP Pre-pump/In-tank mods, Pioneer P5000UB w/XM radio, 4 Infinity Kappa 682.7cf, Fumoto valve, FIAMM Highway blaster horns, SS HPX, IDM mod, DP F5 (Stock,Drive-thru,60T,80E,120,80E-Mountain,1200), Walker BTM, RR, Dieselsite BRV, BTS Tranny (2nd one :-), 31 row tranny cooler, Bilstein shocks, Amsoil bypass oil filter, Stancor HD Glow Plug Relay, billet thermostat housing, front & rear parking cameras, Aux reverse lights, Heated Seats.
Security: CrimeGuard Alarm with remote notification, DIY jimmi-jammers, door cylinder locks and linkage removed, padlocked rear bench seat hinge, PCM, DIY "pitstop" switch.