What you are trying to do is just get a little more time out of the engine before you need to pull the heads and do it correctly. At that time you can decide what upgrades you will make, but for now just buy some springs like the ones you are looking at and put those in. I would just put them back the way they were installed originally to avoid any hassles. When I worked in the marine business we sometimes had to do things to buy a customer a little more time, until they could simply get no more use out of the old setup, then it was time to break out the checkbook.

You might consider just buying a set of something like World Product heads down the road as the cost of doing a good valve job with related upgrades comes pretty close and most times the aftermarket heads are superior in flow and performance. They also usually come setup for roller rockers.

Pat may have a different take on doing that, and he would know best.

Don