Those springs will be too light for an FE hydraulic roller.
Contrary to their ad, there are other beehive spring options if you absolutely just can't machine the heads, but if the heads are off the vehicle, I'd do it right and have the steps cut down around the guides and swap to a modern Viton valve seal size.
If that step is not removed, you're stuck with having to find a conical/beehive spring to fit (narrows down the spring choice and you may be finding a cam to fit the spring, which is not optimal) and also a hardened shim to keep the spring from chewing on the head. A spring locator will not sit down flush.
If you have a mill, you can do this yourself with a pilot-guided cutter that cuts both the guide and the step down. Otherwise, I'd have a shop do it. It's a quick job, maybe if you called them ahead of time, you can have them do it while you're there.