I've used BGA in the past 1/2 the price of INA, and just as good, as said the soft ones are the ones that are noisy, think about what the hydraulic lifter/follower actually does, it is very simply a vessel/cylinder that is supplied with oil UNDER pressure, inside it is a ball and spring the spring pushes the ball onto the seat,(unless some carbon,foreign object stops it) and so holds the pressure inside against the cam trying to push on it, as liquid is not compressible the movement of the cams lobes are transfered as movement of the valve to open.
It will take you about 2-3 hours to strip and clean the valves, the easiest way is to use the flat part at the rear of the normal engineers bench vice, just whack them down on this squarely, do NOT hit them with anything, just a few sharp slams down on this will get the insides out, make sure you slam on the vice as squarely as you can and use the bottom of the follower, you are trying to use the momentum of the insides that want to keep going top pull themselves out.
They do NOT, and should NOT be re oiled other than a very light coating, do not under any circumstances fill the valves, if you do and they expand too much they can hold a valve open, oil doesn't come out, just goes in.
Personally I'd clean out the old ones, diesel/parrafin etc is a good cleaner, not the best by any means, it's more useful as a soaking agent for stubborn nuts/bolts.
It doesn't matter who you use, or what they tell you about block cleanliness, it WILL need cleaning out, this WILL take you the best part of a whole day to clean and prep the block done properly, if the hea dis being re done and has more than about 40-50,000 on it the guides will be shagged, budget around £450 for this, as valves are also likely to be shagged, more so exhaust valves.
When getting new guides try and get COLSHIBO material, it will be the last time it ever needs doing that way, the std material is ok, but not the best, they were built to a price!!
As for taking out machining marks etc, don't waste your time, you'll never notice any difference.
Don't remove any studs in the head, you don't need to unless broken of course, let the machine shop do this, the exhaust studs will need removing for head skim anyway.
If new pistons for £45(for all four) get them pocketed then don't need to worry about future cams, get the flywheel lightened, this will give you a massive difference in comparison to the cost, in acceleration for around £40-£50.
tabetha