Snitz forum password login

[pompaunpo]

Hi, I have a Snitz forum in mysql I want to transfer it in VB.
I have just purchase the license new version 3.6.4, installed and imported all with Impex, I have had of the small initial owed problems essentially to the uppercase name of the tables (while they in the db were all lowecase), and despite that they in the last version of Impex have implemented the variable 'lowercase_table_names'
but 'lowercase_table_names' doesn't work!! I in fact have owed however convert in 000.php all the calls to tables name in lowercase

Now I have the problem of the password that in the snitz forum is HASH SHA256 while VB uses MD5.

I have more than 3000 registered users and I would not want send a email for
change the password access.

I have thought about this solution:

1) I import all 3000 password HASH SHA256 in the [user] table while
the new registered users will have the MD5 password;
2) in login page and more precisely in the file:
includes/functions_login.php

I insert this control:

Code:
if ($user['userid'] < 3000)
{

// if the user id is minor to 3000 therefore is old user
// and he has the HASH SHA256 password

$oldpassword = bin2hex(mhash(MHASH_SHA256,$vbulletin->userinfo['password']));

// "mhash" it a php class that converts the plain text password insert in login
// input text in HASH SHA256

}

// now make the query comparison in the USER table between the field
// [password] and the variable $oldpasswordelse ( if ($user['userid'] > 3000) .....proceed normally
with the MD5 password control

I not being an experienced programmer and not knowing to background
the system of login used from VB I ask to anybody that knows it well
functions_login.php for create these modifications

help me please