You had a bad experience with beehives. Fine. Englert Racing ran Comp beehives on a 2.3 Ford to 9200rpm without issue:
Ford Lima 2300 cam help please - Don Terrill’s Speed-Talk
On the subject of beehive vs conical rpm, there appear to be a few people out there getting decent rpm on beehives (see below).
I know you told me to do my research, but have you?
That's the trouble with talking in absolutes ("99.999% this, 8K that" etc) – you will always find an example that does not conform to your own experiences or opinion. Just sayin'
10K rpm on beehives here:
How high can you REV on these Beehive valve springs? (9K+ fine?) - EvolutionM - Mitsubishi Lancer and Lancer Evolution Community
9K here:
Beehive valve springs: benefits?
8-9K here:
Single valve springs upgrade and rev limit
8+K here:
Beehive spring performance ? - Don Terrill’s Speed-Talk
