so let me get this right. the C blocks are all the same right ?? our 2.7L is the same as the old 3.0L NSX block except the NSX has been bored ? in this case i would just keep a C block over any other block.
here is a little more info on the different blocks
B20A5- 2.0L DOHC non-VTEC- 87-91 Prelude 2.0Si- (135hp)
B20B- 2.0L DOHC non-VTEC- 96-98 CR-V (126hp)
B20Z- 2.0L DOHC non-VTEC- 99-01 CR-V (143hp)
B21A1- 2.1L DOHC non-VTEC- 90-91 Prelude Si (145hp)
K20A3- 2.0L DOHC i-VTEC- '02+ RSX/'02+ Civic Si (160hp)
*K20A2- 2.0L DOHC i-VTEC- '02+ RSX Type S/'02+ Civic Type R (200hp)
*K20A- JDM 2.0L DOHC i-VTEC- '02+ Integra Type R (220ps)
F20A1- JDM 2.0L DOHC non-VTEC- 90-93 Accord Si (155hp)
F20B- JDM 2.0L DOHC VTEC- 90-93 Accord Si-R (190ps)
F20C1- 2.0L DOHC VTEC- '00+ S2000 (250ps/240hp)
F22A1- USDM 2.2L non-VTEC- 92-96 Prelude S/90-93
Accord LX/EX (130hp-135hp)
F22B- USDM 2.2L SOHC VTEC- 94-97 Accord EX, 97 2.2CL (145hp)
*F23A5- USDM 2.3LSOHC 98+ Accord DX (135hp)
*F23A1- USDM 2.3LSOHC VTEC- 98+ Accord EX & LX, 98-99 2.3CL (150hp)
*F23A4- USDM 2.3LSOHC ULEV VTEC- 98+ Accord EX & LX (148hp)
H22A1- USDM 2.2L DOHC VTEC- 92-96 Prelude VTEC (190hp)
H22A4- 2.2L DOHC VTEC- 97-01 Prelude VTEC/SH (97-98: 195hp / 99-01: 200hp)
H22A- JDM 2.2L DOHC VTEC- 92+ Prelude Type-S, 97+ Prelude SiR S Spec. (220ps)
H23A1- USDM 2.2L DOHC non-VTEC- Prelude Si (160hp)
*G25A1- USDM 2.5L SOHC non-VTEC I-5- 96-98 2.5TL (176hp)
*J25A- JDM 2.5L SOHC VTEC V6- (year unknown) JDM Honda
Aspire/Sabre (200ps)
**C27??- USDM 2.7L SOHC non-VTEC V6- 86-89 Legend (150-160hp)
**C27??- USDM 2.7L SOHC non-VTEC V6 - 95-97 Accord V6 (170HP)
C30A(?)- 3.0L DOHC VTEC V6- 91-96 NSX/NSX-T (270hp)
**J30A1 - 3.0L USDM SOHC VTEC V6 - 98-02 Accord V6, 97-99 3.2CL (200hp)
**C32A6 -USDM 3.2L SOHC non-VTEC V6 - 91-95 Legend Sdn, 91-92 Legend Cpe, 96-98 3.2TL (200hp)
**C32A5- USDM 3.2L SOHC non-VTEC V6 - 94-95 Legend GS Sdn, 93-95 Legend Cpe (230hp)
C32A?- 3.2L DOHC VTEC V6- 97+ NSX/NSX-T (290hp)
J32A1- 3.2L USDM SOHC VTEC V6- 98+ 3.2TL/3.2CL (225hp)
J32A2- 3.2L USDM SOHC VTEC V6- 00+ 3.2CL Type-S, 01 3.2TL Type-S (260hp)
**C35A2- 3.5L USDM SOHC non-VTEC V6- 3.5RL (215-225hp)
**J35A1 - 3.5L USDM SOHC VTEC V6 - 98+ Odyessy (210hp)
**J35A3 - 3.5L USDM SOHC VTEC V6 - Acura MDX (240hp)