na engines do have to worry about cam lag though, the added weight is barely noticeable in most applications (worried about weight drive a striped car and maintain a lean body mass index). a turbo car does not need to make an excessive blow off sound if plumbed correctly.... both options have there ups and downs i find the question is not about turbo or NA, V8 or straight 6 ect... its how do you want to make your power (eg low down torque or reving till 11k or somewhere in between) also do you want to go with an engine for and aesthetic reason eg pop culture reference, restoring.
then when its all said and done is it better to spend $30k+ and make a L31ET or $2k and use an RB20det (or RB30ET) and with an other $2k or so get a real close result ~
have fun with your dilemma i decided to build an L31 and one RB20DET one for aesthetics and one for speed and cost