[4BNBAD]

I cut & pasted their email reply.
Bill,
The longest stroke we recommend in a 400 is a 4.000" stroke. At +.030" overbore, this will be a 434 CID. Using this stroke requires extensive clearancing and at least a half-fill of HardBlok due to the fact that when clearancing, you will get into the water jackets. The next step down is a 3.875" stroke (420 CID with +.030" bore). It still requires quit a bit of clearancing but you usually do not get into the water jackets. You can find kit information on our website www.eaglerod.com or by calling us at 662-796-7373.

Thanks for your interest.

Bill back, you can see this is not a street motor it seems 406" is the largest safe driveable 400 sbc.

[4BNBAD]

I called PAW tech line this AM, They have discontinued their 426 kits to many explosions. only offer 420" called super gorilla block all machined ready to assemble, .030 bore & 3.875 stroke using 6" rods, price is $3195 plus shipping
anyone use this big boy?BTW all clearanced to clear crank counterweights
seems to me like a kick *** motor. thoughts, can up grade flat tappet cam to roller cam and kit I upgrade rods to H beam. Bill help brothers of speed!!
The longest stroke we recommend in a 400 is a 4.000" stroke. At +.030" overbore, this will be a 434 CID. Using this stroke requires extensive clearancing and at least a half-fill of HardBlok due to the fact that when clearancing, you will get into the water jackets. The next step down is a 3.875" stroke (420 CID with +.030" bore). It still requires quit a bit of clearancing but you usually do not get into the water jackets. You can find kit information on our website www.eaglerod.com or by calling us at 662-796-7373.

Thanks for your interest.