My swap experience has been swapping a sr20 redtop into a 93 240sx which is literally a connector change and swapping the motor mounts which was cake. Reading what's involved with the IS300 NA-T is actually what persuaded me to plan to go Aristo with the Aristo ECU. The car is my weekend car so inspection and OBD compatibility are not essential however the hard part about NA-T seems to be the tuning. I came from the LS word were tuning is cake but Lexus seems to have made an ECU that likes to kick out a piggy back and run it's stock map, that alone concerned me enough just to say f it and go full Aristo. But no I'm actually not going to be doing the swap myself I'm going to have a guy that works on Supras hopefully handle it for me. Many of my friends own Mk4 supras and all go this guy so I know I'm in good hands.
'12 Scion xb - Daily Driver *Low & Slow*
'02 Lexus IS300 - Weekend Money Pit