Variable hydraulic lifters for 440 engine

This TC does seem a stranger though.
It does flash relatively high but seems a tight model, that it works does not mean it is the right one behind this engine though.
Anyway when time comes i will replace it with something new and known.

So, guess that the question remains..why the manifold vacuum remains low.
I had a look again in my previous posts on FBBO and i always had this low vacuum there, only times i mentioned a higher vacuum was with the engine running at higher idle rpm.
This shitty vacuum did not come because i had the engine opened up, even with the severely advanced cam setup it suffered the same.
And now confirming the engine runs without load caused by the tranny it remains low.
It must be the nature of the beast i guess, this cam in a 440 BB.

So, to come back to the initial idea of using the variable hydraulic lifters.
Think this is the last option of trying to get a street car out of this engine as it is.
I can gain 1-3" vacuum and reduce cam duration with 5-15* @ .050" lift.

Think i will send them an email and ask them some questions and ask for a recommendation.
I wonder what the base height of these lifters are compared to what i am currently using.
If they are same it is ok, if not i might need different length push rods to suit the difference if it is too much.