Ferrea LF1004 63g Lifters - on sale

The lower mass is of zero real (practical, measurable) benefit in all but a very few full-race Slant-6 engines. However, if it's a choice between these and today's off-the-shelf lifters made in China of ground and compressed political dissidents and unwanted girl-children, I'd take the Ferrea lifters in a hurry to avoid the likelihood of having to re-rebuild the engine.

(Fortunately that can remain a thought exercise for now, because there are enough NOS lifters still available for inexpensive money that there's no need to spend big bucks on specialty ones.)