I'm in the process of fitting a set of Kelford cams to a UCF10 Celsior which are in old school speak a "Fast road cam" (270s I think, haven't got the specs in front of me at time of writing) and are able to be used with the standard ECU. Now due to the clients budget it was elected to do this with the engine in place without removing the heads. This has later proved to not be a terribly efficient way of doing the job but fortunately his budget has improved.
Even with the correct tooling and having done this type of job on different engines many times over the years it is quicker and easier in the case of the LS/SC to remove the engine from the car and do the job on an engine stand esp for the novice. It also pays to order in a few spare collets/retainers (which are the same as a 3S-GE) lest anything go "ping" and fly off into the distance and replace the valve stem seals at the same time. Replace the wave washers on the cam scissor gears and remember that when you go to fit the gears to the new cams bung them in the oven for 15-20 mins first (on full and make sure that the mrs isn't around) the scissor gears need to be slotted slightly to clear the new higher lift lobes, opposite the keyway is a good place for this.
I'll let you know how the car performs once the engine is back in the hole
Even with the correct tooling and having done this type of job on different engines many times over the years it is quicker and easier in the case of the LS/SC to remove the engine from the car and do the job on an engine stand esp for the novice. It also pays to order in a few spare collets/retainers (which are the same as a 3S-GE) lest anything go "ping" and fly off into the distance and replace the valve stem seals at the same time. Replace the wave washers on the cam scissor gears and remember that when you go to fit the gears to the new cams bung them in the oven for 15-20 mins first (on full and make sure that the mrs isn't around) the scissor gears need to be slotted slightly to clear the new higher lift lobes, opposite the keyway is a good place for this.
I'll let you know how the car performs once the engine is back in the hole