Value of Big Block Chevy CE Motor???

[iluv69s]

I have been offered a 71 dated 396(402) running motor, recently rebuilt with 4k miles... the stamp is CE350491...cast # 3999290....(supposedly a 4 bolt block-but not sure)291 heads dated June 10 and 18,1969......block is .030 over..6223 crank...dimple rods...11.1 to 1 pistons....Edelbrock X intake..low rise..Compcams solid w 605 lift...roller rockers...750 mighty demon carb...dual feed mech secondary...HEI supercoil...Stock 6 qt pan...Cat fluid damper..motor is running in 70 chevelle...I was considering purchase...any info on block/ head original application?? and how about value?? is there any way to tell if it is definitely a 4 bolt without dropping the pan??

thanks alot guys!!!