.htaccess redirect from WordPress URL to Normal site URL

I have rebuild a site. The old site was WordPress and new site is normal php site with same amount of pages.

I do not want to lose the outside plus google links to this pages and need to do a redirect in .htaccess

I know how to do this with normal links e.g. www.domain1.com/guesthouse.html to www.domain2.com/guesthouse.php

I do not understand the wordpress link with no “.php or .html” at the end of the link.

The old link is www.doamin.com/guesthouse/ (only this without .html or .php)
New link must be www.domain.com/gusethouse.php

The WordPress .htaccess file looks like this

`# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress`

Can I delete the above code and replace with

`Redirect 301 /guesthouse/  http://www.domain.com/guesthouse.php`

or must I add it to the existing .htaccess code.

Do not know how to do it right, please help.

Thank you.