Oil pressure relief valve. Options

[Keith914]

To the "brain trust". Two experienced engineer/mechanics have described the following:
When our Type IV engines are at operating temperature and rpm's exceed about 3,000 the pressure relief valve (ball bearing valve seen in the oil filter bracket) opens up and prevents or reduces oil flow through the filter. Thus, this reduces oil flow through external oil coolers attached via a "pancake" to the engine, greatly reducing there cooling effect when needed most, e.g. at the track. They have altered this valve so that it cannot open, and advised to keep rpm's low until the engine is warmed up -- particularly in cold climates. there are various ways to "plug" this valve, easy when removed from the engine, -- drill and thread a bolt with lock nut to hold the ball bearing closed, press in an aluminum plug, etc.
Two questions: 1) are there other (than too high an oil pressure with cold engine with higher rpm's) unintended consequences, and 2) can this valve be "plugged" and how, without removing the engine to get at it?