I have almost exclusively used p30's with great results and I have built a few lsvtecs in my time...just remember to give the pistons you want to put in the block to the machine shop with the block and the clearances you want so they can get it exact...all castings are different...but definitely go .25 over, every bit helps...

...as for the block guard, I have seen them cause "phantom" overheating problems in the past 8 years...the coolant passages are not sufficient to cool the "combustion" area around the top of the sleeves, leads to little hairline cracks along the rim, this is why golden eagle makes a webbed sleeve to retain the open deck(this is also why honda's run so much cooler comparitively) and as for other solid deck sleeves, they are fine almost all the time they are Iron ductile not cheap honda sleeves...they won't hairline but they will get hot, I used to have solid deck sleeves on an old h22 accord back in the day and it always ran a little hotter than prior...